Fused salt energy storage system

Abstract

The utility model belongs to the technical field of power generation and energy storage, and particularly discloses a fused salt energy storage system. By arranging the heat exchanger, the fused salt energy storage loop is coupled with the host water vapor loop; the controller is arranged and connected with the related pump valves, so that the change of electric power and heat supply requirements can be flexibly responded, the transformation cost is reduced, the reliability of low-load heat supply is improved, and the system is suitable for being popularized and used in small and medium-sized thermal power plants.

Description

Technical Field

[0001] The utility model belongs to the technical field of power generation and energy storage, and specifically discloses a molten salt energy storage system. Background Art

[0002] In recent years, under the background of national energy structure adjustment, the role of thermal power units as supporting and regulating power sources has become increasingly prominent. Among them, the participation of thermal coal-fired units in deep peak regulation and frequent start-up and shutdown has become increasingly normalized. The units often need to be shut down according to the grid dispatch, and the steam supply capacity of a single operating unit can no longer meet the industrial steam demand. At the same time, the fluctuation of industrial steam supply demand further limits the ability of the units to achieve deep peak regulation.

[0003] Molten salt heat storage has been used for a long time and maturely in the field of solar thermal power generation, and engineering practice has proved its feasibility as a relatively safe way of energy storage. With the widespread application of technology, the application fields of high-temperature, large-capacity molten salt heat storage technology have gradually been applied to the flexibility transformation of thermal power units, the use of valley electricity to heat molten salt heat storage to provide industrial steam supply or heating, and other scenarios. However, the available valley electricity is often difficult to match exactly with the amount of molten salt to be heated, resulting in embarrassing conditions where the valley electricity is not fully utilized once the energy storage reaches full capacity, and the peak electricity has to be used for energy storage when the valley electricity is used up.

[0004] If we use valley electricity to heat molten salt for energy storage, and extract main steam and high-temperature reheat steam for heat exchange with molten salt at the same time, the steam generated by heat release can be used to supply heat to the original thermal system, of course, the energy utilization will be more effective in achieving large-capacity heat storage and deep peak regulation. However, the thermal system of this solution is complex, and has a great impact on the thermal system of coal-fired units, and will affect the safe operation of boilers and steam turbines. At the same time, the molten salt heat storage area is far away from the main plant due to safety distance requirements, and the construction cost of high-temperature and high-pressure steam pipelines is also high.

[0005] Therefore, how to couple valley power storage with extracted steam storage and complete pipeline transformation near the power plant so as to flexibly respond to changes in electricity and heating demand, reduce transformation costs and improve the reliability of low-load heating is a problem that technical personnel in this field need to consider. Utility Model Content

[0006] In order to solve the technical problems listed in the background technology, the utility model provides a molten salt energy storage system. The specific technical solution is as follows:

[0007] A molten salt energy storage system comprises a controller, a molten salt energy storage circuit and a main engine water vapor circuit; the molten salt energy storage circuit comprises a molten salt circulation loop of a low-temperature molten salt tank → a molten salt heating and heat exchange module → an electric heater → a high-temperature molten salt tank → a molten salt cooling and heat exchange module → a low-temperature molten salt tank which are sequentially connected through a pipeline; the main engine water vapor circuit comprises a turbine-boiler water vapor circulation loop and a steam extraction branch pipe and a water extraction branch pipe output from the turbine-boiler water vapor circulation loop, the steam extraction branch pipe is connected to an industrial gas supply pipeline through a water vapor passage in the molten salt heating and heat exchange module, the water extraction branch pipe is connected to an industrial gas supply pipeline through a water vapor passage in the molten salt cooling and heat exchange module, the molten salt energy storage circuit and the main engine water vapor circuit are both provided with a pump and a flow control valve group for providing power required for medium circulation, and the pump and the flow control valve group are electrically connected to the controller.

[0008] Preferably, the molten salt cooling and heat exchange module includes a superheater, a steam drum, an evaporator, and a preheater combination that are sequentially connected through pipelines.

[0009] Preferably, the molten salt circulation loop passes through the molten salt cooling and heat exchange module section including the molten salt pipeline in the superheater, the evaporator, and the preheater.

[0010] Compared with the prior art, the utility model has the following advantages:

[0011] The utility model provides a molten salt energy storage system that couples the molten salt energy storage circuit with the main engine water vapor circuit by setting a heat exchanger; by setting a controller and connecting related pumps and valves, it can flexibly respond to changes in electricity and heating demand, reduce transformation costs and improve the reliability of low-load heating. The specific advantages are as follows:

[0012] ⑴ Through the steam-side molten salt heat storage device, the boiler energy output and the turbine energy input are adjusted and balanced, the boiler and turbine operation are decoupled, thereby improving the adjustment range and flexibility of the coal-fired power unit and increasing the peak load regulation capacity of the power system;

[0013] (2) The sensible heat of high-temperature reheated steam is used to heat the molten salt, and the heat originally used to reduce the temperature by spraying water in the desuperheater and pressure reducer is stored through the heat exchanger, thus reducing the loss;

[0014] ⑶ The electrically heated molten salt also serves as salt-making equipment, saving the cost of renting salt-making equipment during the initial installation;

[0015] (4) Use the green electricity from abandoned wind and solar power or low-priced valley electricity in the power system to heat the molten salt from the low-temperature molten salt tank, and store the heat in the high-temperature molten salt tank in the form of sensible heat;

[0016] ⑸ The electric heating device is coupled with the steam heating device, the power of the electric heating device is reduced, and the power supply can be directly used from the factory transformer, reducing the transformer investment;

[0017] (6) The steam heat exchanger is arranged in the steam engine room and the electric heater is arranged in the plant transformer, which saves the cost of high-temperature pipelines and high-voltage cables;

[0018] ⑺The system is simple, has no interference with the original unit's thermal system, does not affect the safety of turbine operation, and is easy to put into operation and cut off;

[0019] ⑻Only cold and hot storage tanks are arranged in the storage tank area, and SGS system steel frames are set up between the storage tanks, and no other buildings are required;

[0020] ⑼ The coupling of electric heating device and steam heating device can more effectively improve the unit's primary frequency regulation capability, AGC response capability, deep peak regulation capability, and rotating reserve compensation capability, which helps coal-fired units to achieve higher profits in the power auxiliary service market. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the molten salt energy storage system in the embodiment of the utility model;

[0022] Among them, 1-steam extraction branch pipe, 2-molten salt heating and heat exchange module, 3-water extraction branch pipe, 4-pump, 5-low-temperature molten salt heat exchanger, 6-evaporator, 7-steam drum, 8-high-temperature molten salt heat exchanger, 9-low-temperature molten salt tank, 10-electric heater, 11-high-temperature molten salt tank, 12-flow control valve group, 13-controller. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model is described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on this embodiment, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] like Figure 1As shown, a molten salt energy storage system provided by an embodiment of the utility model includes a controller 13, a molten salt energy storage circuit and a main engine water vapor circuit; the molten salt energy storage circuit includes a molten salt circulation loop of a low-temperature molten salt tank 9 → a molten salt heating and heat exchange module 2 → an electric heater 10 → a high-temperature molten salt tank 11 → a molten salt cooling and heat exchange module → a low-temperature molten salt tank 9 connected in sequence through a pipeline; the main engine water vapor circuit includes a turbine-boiler water vapor circulation loop and a steam extraction branch pipe 1 and a water extraction branch pipe 3 output from the turbine-boiler water vapor circulation loop, the steam extraction branch pipe 1 is connected to the industrial gas supply pipeline through the water vapor passage in the molten salt heating and heat exchange module, and the water extraction branch pipe 3 is connected to the industrial gas supply pipeline through the water vapor passage in the molten salt cooling and heat exchange module, and the molten salt energy storage circuit and the main engine water vapor circuit are both provided with a pump 4 and a flow control valve group 12 for providing the power required for the medium circulation, and the pump 4 and the flow control valve group 12 are electrically connected to the controller 13.

[0025] The molten salt cooling and heat exchange module comprises a combination of a high-temperature molten salt heat exchanger 8 (i.e. a specific type of superheater), a steam drum 7, an evaporator 6, and a low-temperature molten salt heat exchanger 5 (i.e. a specific type of preheater) which are sequentially connected through pipelines.

[0026] The molten salt circulation loop passes through the molten salt cooling and heat exchange module section including the molten salt pipeline in the high-temperature molten salt heat exchanger 8, the evaporator 6, and the low-temperature molten salt heat exchanger 5.

[0027] During the period of downward peak regulation of coal-fired units, the steam-electric heat storage system, according to the heat balance diagram of No. 1 and No. 2 thermal power units, directly enters the molten salt heating and heat exchange module 2 without passing through the desuperheater and pressure reducer in the original extraction branch pipe 1 of the unit; at the same time, the pump 4 pumps the low-temperature molten salt (about 200°C) in the low-temperature molten salt tank 9 into the molten salt heating and heat exchange module 2, and fully exchanges heat with the high-temperature reheated steam to achieve the first step of heating. The steam after heat exchange can be used for industrial steam supply. Subsequently, the electric heater 10 uses new energy green electricity or low-priced valley electricity to heat the medium-temperature molten salt from the molten salt heating and heat exchange module 2 to 400°C, and the high-temperature molten salt stores heat in the high-temperature molten salt tank 11 in the form of sensible heat. In order to increase the flexibility and safety of the steam-electric heat storage system, a branch pipe is branched from the extraction branch pipe 1 to the high-temperature reheat steam pipeline after pressure regulation, which is used to adjust the load of the molten salt steam heat exchanger.

[0028] During the period of upward peak load regulation of coal-fired units or during the peak electricity price period, the steam generation system will pump the feed water from the deaerator of the thermal power unit into the low-temperature molten salt heat exchanger 5, the evaporator 6, the steam drum 7, and the high-temperature molten salt heat exchanger 8 in sequence through the pump 4; at the same time, the molten salt heat release system will pump the high-temperature molten salt (about 400°C) in the high-temperature molten salt tank 11 into the high-temperature molten salt heat exchanger 8, the evaporator 6, and the low-temperature molten salt heat exchanger 5 in sequence through the pump 4, fully exchange heat with water and generate high-temperature steam for industrial steam supply, and the high-temperature molten salt will become low-temperature molten salt (about 200°C) and return to the low-temperature molten salt tank 9 to complete the heat release process. In order to increase the flexibility and safety of the steam generation system, a branch pipe is separated from the water pumping branch pipe 3 to the desuperheater to adjust the parameters of the steam generation system for external steam supply. The controller 13 flexibly controls the start and stop of the pump 4 in all circuits and the opening and closing of the flow control valve group 12 according to the peak and valley fluctuations of the electricity price, the energy storage capacity and the steam demand of the subsequent pipeline.

[0029] Finally, it should be noted that the above are only 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 above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A molten salt energy storage system, characterized in that: It includes a controller, a molten salt energy storage circuit and a main engine water vapor circuit; the molten salt energy storage circuit includes a molten salt circulation loop of a low-temperature molten salt tank → a molten salt heating and heat exchange module → an electric heater → a high-temperature molten salt tank → a molten salt cooling and heat exchange module → a low-temperature molten salt tank which are sequentially connected through a pipeline; the main engine water vapor circuit includes a turbine-boiler water vapor circulation loop and a steam extraction branch pipe and a water extraction branch pipe output from the turbine-boiler water vapor circulation loop, the steam extraction branch pipe is connected to the industrial gas supply pipeline through the water vapor passage in the molten salt heating and heat exchange module, the water extraction branch pipe is connected to the industrial gas supply pipeline through the water vapor passage in the molten salt cooling and heat exchange module, the molten salt energy storage circuit and the main engine water vapor circuit are both provided with a pump and a flow control valve group for providing the power required for the medium circulation, and the pump and the flow control valve group are electrically connected to the controller.

2. A molten salt energy storage system according to claim 1, characterized in that: The molten salt cooling and heat exchange module comprises a superheater, a steam drum, an evaporator and a preheater combination which are sequentially connected through pipelines.

3. A molten salt energy storage system according to claim 2, characterized in that: The molten salt circulation loop passes through the molten salt cooling and heat exchange module section including the molten salt pipeline in the superheater, the evaporator, and the preheater.

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