CN103868389A - Independent fused salt heat storage power plant - Google Patents

Abstract

An independent fused salt heat storage power plant belongs to the technical field of energy storage, and comprises a power supply, an electric fused salt heater, a high-temperature hot salt tank, a low-temperature cold salt tank, a fused salt pump, a fused salt circuit system, a brine heat exchanger, a conventional power generation island, a water-steam circuit system and an intelligent control system. When unstable or redundant electric energy such as photovoltaic power, wind power and off-peak power is stored, the electric energy is converted into high-temperature heat energy to be stored in the high-temperature fused salt through heating the high-temperature fused salt by the electric fused salt heater. When electricity utilization is needed, high-temperature heat energy stored in the high-temperature fused salt can heat water to generate water steam to drive a steam turbine to generate power to realize the energy release. In addition, a large-scale high-temperature thermal storage power plant built in cities can also be combined with city heat supply to construct a large-scale high-temperature heat storage and combined heat and power supply station.

Description

An independent molten salt heat storage power station

technical field

The invention relates to an independent heat storage power station system, in particular to an independent heat storage power station system using mixed molten salt as a heat storage working fluid, and belongs to the technical field of energy storage.

Background technique

According to my country's "12th Five-Year Plan for Renewable Energy Development", by 2020, the installed capacity of wind power and solar energy will reach 200 million kW and 50 million kW respectively. However, the inherent intermittency and volatility of renewable energy such as wind energy and solar energy have a great impact on the power grid, resulting in a high proportion of wind power and photovoltaic power generation not connected to the grid in my country, and severe wind/solar abandonment. For example: in 2011, the unconnected rate of wind power in my country reached 28%; the unconnected rate of photovoltaic power reached 29%; The average rate of wind abandonment is 20%, reaching 40% in some areas. If the problem of large-scale access to wind and solar energy is not resolved, by 2015 and 2020, 33 million tons and 70 million tons of standard coal will be lost each year, respectively. In addition, in order to meet the requirements of power load, the current installed capacity of power generation and grid capacity are built according to the maximum demand. As the peak-to-valley difference of the power grid increases day by day, it will inevitably lead to the shutdown or low-load operation of generator sets during off-peak power consumption, and Waste of grid capacity. In 2011, the total load factor of conventional coal-fired generating units nationwide was only 51.8%, and the load utilization factor of the power grid was also less than 55%. The independent molten salt heat storage power station using molten salt as heat storage medium can convert these unstable or redundant electric energy into thermal energy and store it in high temperature molten salt, and then convert it into electric energy when electricity is needed. It can realize the smooth fluctuation of renewable energy, tracking and dispatching output, peak regulation and frequency regulation, etc., so that the output of renewable energy power generation can be stabilized and controlled, and meet the requirements of large-scale access and grid connection of renewable energy power. It can also greatly improve the actual operating efficiency of thermal power units and enhance the power transmission capacity of the power grid.

Contents of the invention

In view of the deficiencies in the prior art, the present invention provides a method of heating high-temperature molten salt by using wind power, photovoltaic power, low-peak power and other power quality unstable or redundant electric energy, and the high-temperature heat energy is stored in the high-temperature molten salt. When electricity is needed, the high-temperature thermal energy stored in high-temperature molten salt is used to heat water to generate water vapor, thereby driving a steam turbine to generate electricity and realizing energy release. An independent molten salt heat storage power station system.

The independent molten salt thermal storage power station is characterized in that it includes a power supply 1, a molten salt electric heater 2, a high-temperature hot salt tank 3, a low-temperature cold salt tank 4, a first molten salt pump 5, a second salt pump 6, a salt water Heat exchanger (steam generator) 7, power generation island 8; power supply 1 is connected with molten salt electric heater 2, and the outlet of electric heater 2 is connected with high-temperature hot salt tank 3 and brine heat exchanger ( or steam generator) 7. The low-temperature cold salt tank 4 is connected, and then the cold salt tank 4 is connected to the inlet of the molten salt electric heater 2, and on the pipeline between the outlet of the electric heater 2 and the high-temperature hot salt tank 3 There is a molten salt heater outlet temperature sensor 12, a hot salt pipeline pressure sensor 20, a hot salt pipeline temperature sensor 22, a hot salt pipeline flow sensor 24, and a hot salt tank 3 at a high temperature and a brine heat exchanger (steam generation The second salt pump 6 is provided on the pipeline between the electric heater 7 and the first molten salt pump 5 and the inlet temperature sensor of the molten salt heater are provided on the pipeline between the molten salt electric heater 2 and the low-temperature cold salt tank 4 13. Cold salt pipeline pressure sensor 21, cold salt pipeline temperature sensor 23, cold salt pipeline flow sensor 25; molten salt electric heater 2, high temperature hot salt tank 3, low temperature cold salt tank 4, first molten salt The salt pump 5, the second salt pump 6, and the brine heat exchanger (steam generator) 7 form a molten salt loop system; the brine heat exchanger 7 forms a water-steam loop through the pipeline and the power generation island 8, and drives the steam turbine to generate electricity.

The power source 1 may be a wind power station, a photovoltaic power station, a smart grid energy storage station or other power stations with unstable power.

The thermal storage power station uses mixed molten salt as the thermal storage working medium, and converts excess electric energy or unstable electric energy generated by various power stations into high-temperature heat energy and stores it in the high-temperature molten salt.

The thermal storage power station can be combined with urban heating, and the exhaust gas after power generation can be used to heat municipal water to realize combined heat and power supply. The molten salt electric heater 2 adopts a serpentine circular tube 11 as a heating element. There is a shell on the outside of the serpentine circular tube 11, and the shell is respectively provided with an outlet and an inlet, wherein the molten salt heater outlet temperature sensor 12, the molten salt heating Device inlet temperature sensor 13 is used for monitoring the temperature of heating molten salt outlet and inlet.

The hot salt tank 3 is equipped with a hot salt tank temperature sensor 15, the upper part of the hot salt tank 3 is provided with a liquid level monitoring port 17 of the hot salt tank, and the lower part is provided with a salt discharge port 19 of the hot salt tank; Tank temperature sensor 14, cold salt tank 4 upper part is provided with cold salt tank liquid level monitoring port 16, and the lower part is provided with cold salt tank salt discharge port 18.

The first molten salt pump 5 and the second molten salt pump 6 that provide power for the molten salt are respectively installed on the top of the cold salt tank 4 and the hot salt tank 3, and two molten salt pumps are installed on the top of each tank, one for use and one for standby The tank is equipped with temperature sensors 14,15 for monitoring temperature, monitoring ports 16,17 for monitoring liquid level, and salt discharge ports 18,19 for emptying molten salt.

The molten salt circuit system (large dashed box) includes all piping systems for carrying molten salt, as well as pressure sensors 20, 21, temperature sensors 22, 23, and flow sensors 24, 25 installed on the piping systems.

The brine heat exchanger 7 adopts a shell-and-tube structure, the molten salt is in the tube-side system, and the water is in the shell-side system, and the two adopt the form of forced convection heat exchange for heat exchange.

Conventional power generation island 8 adopts steam turbine to generate electricity, and its principle and composition are consistent with existing mainstream technology.

An urban heating system is also provided in the water-steam circuit formed by the brine heat exchanger 7 and the power generation island 8 . The principle and composition of the urban heating system 9 here are consistent with the existing mainstream technology.

The water-steam loop system (small dotted line box), includes all piping systems used to carry water or steam, and various sensors installed on the piping systems, such as pressure, temperature, flow sensors, etc.

It also includes an intelligent control system 10, and the intelligent control system 10 is respectively connected with the power supply, various sensors and the like.

The beneficial effects of the present invention are: the independent molten salt heat storage power station converts unstable or redundant electric energy into thermal energy and stores it in the high-temperature molten salt, and when electricity is needed, the high-temperature thermal energy stored in the high-temperature molten salt is used to heat water to generate steam , so as to drive the steam turbine to generate electricity and realize energy release. Compared with compressed air energy storage and pumped storage power stations, independent molten salt heat storage power stations have the advantages of small footprint, are not restricted by geographical conditions, and can be built inside cities. In addition, large-scale high-temperature heat storage power stations built in cities It can also be combined with urban heating to build a large-scale high-temperature heat storage power station. After realizing combined heat and power supply, the efficiency of the heat storage power station can be increased from the original 30% to more than 70%. This efficiency is different from the current pumped storage Energy-saving power plants have the same efficiency, but the cost is lower than that of pumped hydro storage and compressed air storage power plants. Therefore, high temperature heat storage power station is a large-scale physical energy storage technology with broad development prospects. The independent molten salt heat storage power station can be used for energy storage of photovoltaic and wind power stations, and solve the problems of wind and light abandonment in wind power generation and photovoltaic power generation. Independent molten salt heat storage power stations can also be used in smart grid energy storage power stations to realize the time-space decoupling of power generation and power consumption, delay and reduce the construction of power grids, and improve energy utilization efficiency and overall asset utilization of the grid.

The so-called independent molten salt heat storage power station is to use photovoltaic power, wind power, low-peak power and other unstable or redundant electric energy to store energy. When electricity is needed, the high-temperature heat energy stored in the high-temperature molten salt is used to heat water to generate water vapor, thereby driving the steam turbine to generate electricity and realizing energy release. It is characterized in that it includes power supply, molten salt electric heater, high temperature hot salt tank, low temperature cold salt tank, molten salt pump, molten salt loop system, brine heat exchanger (steam generator), conventional power generation island, water -Steam circuit system and intelligent control system. In addition, large-scale high-temperature heat storage power stations built in cities can also be combined with urban heating to build large-scale high-temperature heat storage cogeneration power stations. The independent molten salt heat storage power station can be used for energy storage of photovoltaic and wind power stations, and solve the problems of wind and light abandonment in wind power generation and photovoltaic power generation. The independent molten salt heat storage power station can also be used in the smart grid energy storage power station to realize the time-space decoupling of power generation and power consumption, and it can be used for power grid peak regulation, delay and reduce the construction of power grid, and improve energy utilization efficiency and overall asset utilization of the power grid.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

In the figure: 1. Power supply, 2. Molten salt electric heater, 3. High temperature hot salt tank, 4. Low temperature cold salt tank, 5. The first molten salt pump, 6. The second molten salt pump, big dashed box is the molten salt circuit system, 7. brine heat exchanger (steam generator), 8. conventional power generation island, 9. urban heating system, the small dashed box is the water-steam circuit system, 10. intelligent control system, 11. snake 12. Outlet temperature sensor of molten salt heater, 13. Inlet temperature sensor of molten salt heater, 14. Temperature sensor of cold salt tank, 15. Temperature sensor of hot salt tank, 16. Liquid level monitoring port of cold salt tank , 17. Liquid level monitoring port of hot brine tank, 18. Salt discharge port of cold brine tank, 19. Salt discharge port of hot brine tank, 20. Pressure sensor of hot brine pipeline, 21. Pressure sensor of cold brine pipeline, 22. Salt pipeline temperature sensor, 23, cold salt pipeline pressure sensor, 24, hot salt pipeline flow sensor, 25, cold salt pipeline flow sensor.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Example 1

As shown in Figure 1, an independent thermal storage power station using molten salt as the thermal storage medium includes a power supply for providing electric energy, a molten salt heating system, a molten salt heat storage system, a molten salt heat exchange system, a power generation island and an urban power supply system. The thermal system, the specific structure is as follows:

The power source can be a wind power station, a photovoltaic power station, a smart grid energy storage station or other power stations with unstable power, or urban low-peak electricity. The thermal storage power station uses mixed molten salt as the thermal storage medium. The mixed molten salt has many advantages such as large heat capacity, good thermal stability, low viscosity, low vapor pressure, wide liquid temperature range, and low cost. The excess electric energy or unstable electric energy generated by different forms of power stations is converted into high-temperature heat energy and stored in high-temperature molten salt. The molten salt electric heater 2 uses a serpentine circular tube 11 as a heating element, which is less limited by thermal stress and has a faster start-up speed, which is suitable for frequent power supply start-stop and variable load operation requirements. The molten salt heat storage system adopts a double-tank arrangement structure, which includes a cold salt tank 4 for storing low-temperature molten salt and a hot salt tank 3 for storing high-temperature molten salt, both of which are cylindrical in structure. Stainless steel, dome cover, external insulation, vertical placement. The cold salt tank 4 is used to store the low-temperature molten salt released by the heat exchange system at the initial stage of system startup or during operation, and the hot salt tank 3 is used to store the high-temperature molten salt heated by the molten salt heater; in the cold salt tank 4 Two low-temperature molten salt pumps 5 and two high-temperature molten salt pumps 6 are installed on the top of the hot salt tank 3 respectively, both of which are in the form of one for use and one for standby, so as to prevent accidents of the entire system caused by failure of the molten salt pump. The molten salt pumps are all long-axis submerged pumps, which are installed vertically on the top. Both the cold salt tank 4 and the hot salt tank 3 are provided with liquid level monitoring ports 16 and 17, and the safe liquid level of the molten salt can be fed back through the liquid level sensor. Both are equipped with temperature sensors 14, 15 for monitoring the temperature of both. Salt discharge outlets 18 and 19 for molten salt are designed at the bottom of the salt tank to empty the molten salt during accidents or routine maintenance.

The molten salt loop system includes a hot salt pipeline, a cold salt pipeline, and pressure sensors 20, 21, temperature sensors 22, 23, and flow sensors 24, 25 on the pipelines. These sensors transmit signals to the controller 10, and the controller 10 synthesizes these signals to continuously adjust the frequency of the high temperature molten salt pump 6 and the low temperature molten salt pump 5 to meet different operating conditions.

The water-steam loop system includes all pipelines in power generation islands and urban heating systems and pressure sensors, temperature sensors, flow sensors, etc. on the pipelines.

The thermal storage power station can be combined with urban heat supply, and the waste steam after power generation can be used to heat municipal water to realize cogeneration of heat and power. Thereby improving the efficiency of the whole power station.

In addition, the molten salt heat exchange equipment adopts the arrangement of the molten salt on the shell side and the high-pressure water/steam on the pipe side, thereby greatly reducing the shell wall and saving costs. It is also conducive to emptying the molten salt during system accidents or routine maintenance .

Working principle and realization process of the present invention are as follows:

When the power supply has power output and needs energy storage, the molten salt electric heater is started, and the low-temperature molten salt (about 200°C) drawn from the low-temperature tank by the low-temperature molten salt pump is heated to a high temperature (about 500°C), and then store the high-temperature molten salt in the hot salt tank, which realizes the conversion of electrical energy into heat energy. When electricity is needed or during the peak period of electricity consumption, the molten salt pump on the top of the hot salt tank is started, and the high-temperature molten salt is continuously transported to the brine heat exchanger, that is, the steam generator heats water to generate steam to drive the steam turbine to generate electricity. This process realizes The conversion of thermal energy into electrical energy, while the high-temperature molten salt continuously releases heat and turns into low-temperature molten salt and returns to the cold salt tank to complete a cycle. In addition, the exhaust steam generated by the steam turbine can enter the urban heat supply and heat exchange system, and the water that becomes low temperature after heating the municipal water enters the brine heat exchanger for the next heat exchange.

The whole system is realized through the microcomputer controller namely 10 intelligent control. The microcomputer controller intelligently adjusts the start-stop and heating power of the molten salt electric heater through the feedback signals of the temperature sensor and the flow sensor, and adjusts the frequency of the molten salt pump in the cold and hot salt tanks to control the flow of the molten salt to meet the needs of users. end different needs.

Claims (9)

1. An independent molten salt heat storage power station, characterized in that it includes a power supply, a molten salt electric heater, a high-temperature hot salt tank, a low-temperature cold salt tank, a first molten salt pump, a second salt pump, a brine heat exchanger, Power generation island; the power supply is connected to the molten salt electric heater, and the outlet of the electric heater is connected to the high-temperature hot salt tank, the brine heat exchanger, and the low-temperature cold salt tank in turn through the pipeline, and then the cold salt tank is connected to the molten salt electric heater. The inlet connection of the heater, the outlet temperature sensor of the molten salt heater, the pressure sensor of the hot salt pipeline, the temperature sensor of the hot salt pipeline, the hot salt pipe A second salt pump is installed on the pipeline between the high-temperature hot salt tank and the brine heat exchanger, and a first molten salt pump is installed on the pipeline between the molten salt electric heater and the low-temperature cold salt tank , molten salt heater inlet temperature sensor, cold salt pipeline pressure sensor, cold salt pipeline temperature sensor, cold salt pipeline flow sensor; molten salt electric heater, high temperature hot salt tank, low temperature cold salt tank, the first The molten salt pump, the second salt pump, and the brine heat exchanger form a molten salt loop system; the brine heat exchanger forms a water-steam loop through the pipeline and the power generation island, and drives the steam turbine to generate electricity. 2. The independent molten salt heat storage power station according to claim 1, wherein the power source is a wind power station, a photovoltaic power station, a smart grid energy storage station or other power stations with unstable power. 3. The independent molten salt thermal storage power station according to claim 1, wherein the molten salt uses mixed molten salt as the thermal storage working medium. 4. According to the described independent molten salt thermal storage power station according to claim 1, it is characterized in that, the molten salt electric heater adopts a serpentine circular tube as a heating element, and the outer surface of the serpentine circular tube has a shell, and the shells are respectively An outlet and an inlet are provided, wherein the temperature sensor and the inlet temperature sensor of the molten salt heater are used to monitor the temperature of the outlet and the inlet of the heated molten salt. 5. According to the described independent molten salt heat storage power station according to claim 1, it is characterized in that a temperature sensor for the hot salt tank is installed on the hot salt tank, the upper part of the hot salt tank is provided with a liquid level monitoring port of the hot salt tank, and the lower part is provided with a temperature sensor for the hot salt tank. There is a salt discharge port of the hot brine tank; a temperature sensor of the cold brine tank is installed on the cold brine tank, the liquid level monitoring port of the cold brine tank is installed on the upper part of the cold brine tank, and the salt discharge port of the cold brine tank is set on the lower part. 6. The independent molten salt heat storage power station according to claim 1, characterized in that the tops of the cold salt tank and the hot salt tank are respectively equipped with a first molten salt pump and a second molten salt pump to provide power for molten salt , There are two molten salt pumps installed on the top of each tank, one for use and one for standby. 7. The independent molten salt heat storage power station according to claim 1, characterized in that the brine heat exchanger adopts a shell-and-tube structure, the molten salt is in the tube-side system, and the water is in the shell-side system. Forced convection heat transfer is used for heat transfer. 8. According to the described independent molten salt heat storage power station according to claim 1, it is characterized in that, in the water-steam circuit formed by the brine heat exchanger and the power generation island, an urban heating system is also provided, and the water outlet pipeline of the power generation island A heat exchange system is connected in the middle, and the heat exchange system is connected with the urban heating system. 9. The independent molten salt heat storage power station according to claim 1, further comprising an intelligent control system 10, the intelligent control system is connected with the power supply, the first molten salt pump, the second salt pump and the molten salt circuit respectively The sensor in the sensor is connected to the sensor in the water-steam circuit.

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