A photo-thermal energy storage power generation system

Abstract

This invention discloses a solar thermal energy storage and power generation system, comprising: a first storage tank, a second storage tank, a heat absorption tower, a heat absorber, a cryogenic pump, and a power generation system. The first storage tank is vertically positioned higher than the second storage tank. The heat absorber is mounted on the heat absorption tower. The outlet of the second storage tank is connected to the inlet of the heat absorber and the inlet of the first storage tank via the cryogenic pump. The outlet of the heat absorber is connected to the inlet of the first storage tank. The outlet of the first storage tank is connected to the power generation system. The power generation system converts the gravitational potential energy and thermal energy of the heat transfer medium in the first storage tank into electrical energy. The outlet of the heat transfer medium of the power generation system is connected to the inlet of the second storage tank. This invention stores the input power of the cryogenic pump through gravitational potential energy, achieving high energy storage efficiency (greater than 75%), recovering consumed plant power to increase grid-connected power; simultaneously, it can efficiently store abandoned photovoltaic power, reducing the power system's power curtailment rate, while converting gravitational potential energy into electrical energy.

Description

Technical Field

[0001] This invention belongs to the field of solar thermal power generation technology, and particularly relates to an energy storage power generation system. Background Technology

[0002] With the introduction of the "dual carbon" target, the proportion of new energy in the power system is gradually increasing, and the phenomenon of curtailment of electricity is becoming more prominent. Concentrated solar power (CSP) plants are equipped with large-scale and inexpensive molten salt energy storage systems, thus providing smooth, stable, and dispatchable power output, and have broad application prospects under the "dual carbon" background. Tower CSP plants have high power generation efficiency and low cost per kilowatt-hour, giving them a significant advantage over parabolic trough CSP plants. Furthermore, adding an electric heating system can complement photovoltaic (PV) power, absorbing curtailed wind and solar power. However, the electric heating system converts electrical energy into heat energy, resulting in low thermoelectric efficiency (<50%), which in turn leads to low molten salt energy storage efficiency.

[0003] Furthermore, to ensure the efficiency of the heliostat field, the receivers in tower-type concentrated solar power (CSP) plants are typically required to be installed at a relatively high height; currently, the height of receiver towers in commercial CSP plants is over 200 meters. The cold salt pump consumes a significant amount of plant power to pump molten salt into the receiver at the top of the receiver tower, reducing the power output of the CSP plant to the grid. Summary of the Invention

[0004] This invention provides a solar thermal energy storage power generation system that stores the input power of a cryogenic pump through gravitational potential energy, achieving high energy storage efficiency (greater than 75%). It recovers consumed plant power to increase grid-connected power, and the first storage tank stores solar energy in the form of thermal energy. At the same time, it can also efficiently store abandoned photovoltaic power, reducing the power abandonment rate of the power system, and converting gravitational potential energy into electrical energy.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A solar thermal energy storage power generation system includes: a first storage tank, a second storage tank, a heat absorption tower, a heat absorber, a cryogenic pump, and a power generation system;

[0007] The first storage tank is positioned higher than the second storage tank in the vertical direction. The heat absorber is installed on the heat absorption tower. The outlet of the second storage tank is connected to the inlet of the heat absorber and the inlet of the first storage tank through the cryogenic pump. The outlet of the heat absorber is connected to the inlet of the first storage tank. The outlet of the first storage tank is connected to the power generation system. The power generation system is used to convert the gravitational potential energy and thermal energy of the heat transfer medium in the first storage tank into electrical energy. The outlet of the heat transfer medium of the power generation system is connected to the inlet of the second storage tank.

[0008] The power generation system includes a thermal power generation system, a potential power generation system, and a generator, wherein the thermal power generation system and the potential power generation system are both connected to the generator.

[0009] The thermal power generation system includes an evaporator, a superheater, a condenser, and a steam turbine; the potential energy power generation system includes a liquid turbine.

[0010] The heat transfer medium in the first storage tank passes through the superheater and evaporator in sequence to exchange heat with the water in the thermal power generation system. The heat transfer medium passing through the evaporator enters the second storage tank via the liquid turbine. The water in the superheater passes through the steam turbine, condenser and evaporator in sequence to complete the circulation.

[0011] The hydraulic turbine includes a hydraulic turbine body, which includes a hydraulic turbine shaft and blades. The blades are fixedly installed on the hydraulic turbine shaft, and the hydraulic turbine shaft and blades are provided with channels communicating with a thermal power generation system.

[0012] The channel is connected to the condenser at one end and to the evaporator at the other end.

[0013] The heat transfer medium in the first storage tank drives the hydraulic turbine while preheating the water flowing through the channel; at the same time, the water in the channel also cools the turbine shaft and blades, reducing material costs.

[0014] The hydraulic turbine also includes a hot water manifold and a cold water manifold.

[0015] The hot water header is connected to the inlet of the evaporator. The hot water header is located between the turbine body and the generator. The turbine shaft and the generator shaft are connected inside the hot water header. The condenser outlet is connected to the inlet of the cold water header.

[0016] A feedwater pump is also installed between the cold water header and the condenser.

[0017] Because the present invention adopts the above technical solution, it has the following advantages and positive effects compared with the prior art:

[0018] 1. In one embodiment of the present invention, the first storage tank is positioned at a high location, with its vertical orientation higher than that of the second storage tank. This allows the plant power supplied by the cryogenic pump to be stored as gravitational potential energy, while the heat transfer medium in the first storage tank, after absorbing solar energy, stores it as thermal energy. This method of energy storage has high efficiency (greater than 75%), recovering a large amount of consumed plant power to increase grid power output and reduce the cost per kilowatt-hour of the solar thermal power plant. Utilizing gravitational potential energy to store power curtailment and off-peak electricity from the power system results in high energy storage efficiency, achieving low-cost and high-efficiency energy storage, increasing the grid's capacity to absorb curtailed power, and realizing "peak shaving and valley filling." It can also efficiently store curtailed photovoltaic power, reducing the curtailment rate of the power system. The high-temperature medium within the high-temperature medium generates electricity through gravitational potential energy, avoiding the use of a high-temperature pump in the solar thermal power plant, further reducing plant power consumption, lowering equipment investment costs while increasing grid power output.

[0019] 2. In another embodiment of the present invention, the thermal energy of the high-temperature medium can be converted into electrical energy while generating electricity using the gravitational potential energy of the high-temperature medium. The hydraulic turbine serves as the preheating section of the thermal power generation system. While converting potential energy, the hydraulic turbine heats water to saturated water, avoiding the use of preheaters and other equipment, simplifying the system, and reducing equipment costs and layout space. Furthermore, the cold water passing through the channel between the hydraulic turbine shaft and the blades greatly reduces the material temperature, which can reduce the difficulty of material selection on the one hand, and increase the life of the material on the other hand. Attached Figure Description

[0020] Figure 1 This is a structural diagram of the solar thermal energy storage power generation system of Embodiment 1 of the present invention;

[0021] Figure 2 This is a structural diagram of the hydraulic turbine of Embodiment 1 of the present invention;

[0022] Figure 3 for Figure 2 A magnified view of A in the middle.

[0023] Explanation of reference numerals in the attached drawings: 1-Absorber; 2-First storage tank; 3-Superheater; 4-Evaporator; 5-Hydraulic turbine; 501-Hot brine inlet; 502-Blade; 503-Hydraulic turbine shaft; 504-Cold brine outlet; 505-Cold water header; 506-Hot water header; 507-Outer shell; 508-Hot water outlet; 6-Steam turbine; 7-Generator; 8-Condenser; 9-Feed water pump; 10-Second storage tank; 11-Cryogenic pump. Detailed Implementation

[0024] The present invention provides a solar thermal energy storage power generation system in further detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description.

[0025] Example 1

[0026] See Figure 1-2 A solar thermal energy storage power generation system includes: a first storage tank 2, a second storage tank 10, a heat absorption tower, a heat absorber 1, a cryogenic pump 11, and a power generation system; in this embodiment, the heat transfer medium is molten salt, but it can also be other heat transfer media, such as oil, etc. The first storage tank 2 is a hot salt tank, and the second storage tank 10 is a cold salt tank.

[0027] The first storage tank 2 is positioned higher than the second storage tank 10 in the vertical direction. The heat absorber 1 is located at the top of the heat absorption tower. The outlet of the second storage tank 10 is connected to the inlet of the heat absorber 1 and the inlet of the second storage tank 2 via a cryogenic pump 11. The outlet of the heat absorber 1 is connected to the inlet of the first storage tank 2. The outlet of the first storage tank 2 is connected to a power generation system. The power generation system is used to convert the gravitational potential energy and thermal energy of the heat transfer medium in the first storage tank 2 into electrical energy. The outlet of the heat storage medium of the power generation system is connected to the inlet of the second storage tank 10.

[0028] By placing the first storage tank 2 at a higher position, so that its vertical orientation is higher than that of the second storage tank 10, the plant power supplied by the cryogenic pump 11 can be stored as gravitational potential energy. At the same time, the heat transfer medium in the first storage tank, after absorbing solar energy, stores it as thermal energy. This form of energy storage has high efficiency (greater than 75%), recovering a large amount of consumed plant power to increase grid power and reduce the cost per kilowatt-hour of the solar thermal power plant. Utilizing gravitational potential energy to store power curtailment and off-peak electricity from the power system is highly efficient, achieving low-cost and high-efficiency energy storage, increasing the grid's capacity to absorb curtailed power, and realizing "peak shaving and valley filling." It can also efficiently store curtailed photovoltaic power, reducing the curtailment rate of the power system. The high-temperature medium in the high-temperature medium generates electricity through gravitational potential energy, avoiding the use of high-temperature pumps in the solar thermal power plant, further reducing plant power consumption, lowering equipment investment costs, and increasing grid power.

[0029] The power generation system includes a thermal power generation system, a potential power generation system, and a generator 7. The thermal power generation system includes an evaporator 4, a superheater 3, a steam turbine 6, and a condenser 8. The potential power generation system includes a hydraulic turbine 5. Both the hydraulic turbine 5 and the steam turbine 6 are connected to the generator 7.

[0030] The heat transfer medium in the first storage tank 2 passes through the superheater 3 and the evaporator 4 in sequence to exchange heat with the water in the thermal power generation system. The heat transfer medium passing through the evaporator 4 enters the second storage tank 10 via the liquid turbine 5. The water in the superheater 3 passes through the steam turbine 6, the condenser 8, and the evaporator 4 in sequence to complete the circulation.

[0031] The hydraulic turbine 5 includes a hydraulic turbine body, which includes a housing 507 and a hydraulic turbine shaft 503 and blades 502 disposed within the housing 507. The blades 502 are fixedly mounted on the hydraulic turbine shaft 503. A channel communicating with the thermal power generation system is provided between the blades 502 and the hydraulic turbine shaft 503. One end of the channel is connected to the condenser 8, and the other end is connected to the evaporator 4.

[0032] The high-temperature medium molten salt flows downwards under the action of gravity. After flowing into the hydraulic turbine 5, it drives the blades 502 of the hydraulic turbine 5 to rotate and do work, releasing gravitational potential energy. The rotating blades 502 do work, and the hydraulic turbine shaft 503 is connected to the generator 7, which converts mechanical energy into electrical energy.

[0033] During the process of releasing gravitational potential energy, the high-temperature medium simultaneously converts the heat energy carried by the high-temperature medium into electrical energy. The heat energy is then transferred to the water through the steam turbine 5, superheater 3, and evaporator 4, causing the liquid water to be converted into water vapor, which drives the steam turbine 6 to do work and convert it into electrical energy.

[0034] The hydraulic turbine 5 heats water to saturate while converting potential energy. A water channel is set between the blade 502 and the hydraulic turbine shaft 503. This avoids the use of equipment such as molten salt preheaters, reducing equipment costs and layout space. Secondly, the hydraulic turbine shaft 503 and blade 502 are cooled by water, which greatly reduces the surface temperature of the materials. This reduces the difficulty of material selection and increases the lifespan of the materials.

[0035] The hydraulic turbine 5 also includes a hot water header 506 and a cold water header 505, with a channel connecting the hot water header 506 and the cold water header 505;

[0036] The outlet of the hot water header 506 is connected to the inlet of the evaporator 4. The hot water header 506 is located between the turbine body and the generator 7. The turbine shaft 503 and the generator shaft are connected inside the hot water header 506. A channel is provided inside the hot water header 506 to connect to the hot water outlet 508 of the hot water header 506 (see details). Figure 2 and Figure 3 The outlet of condenser 8 is connected to the inlet of cold water header 505.

[0037] A feedwater pump 9 is also installed between the cold water header 505 and the condenser 8.

[0038] The energy storage power generation principle of this embodiment is as follows:

[0039] The cryogenic pump 11 pumps cold salt from the lower-level second storage tank 10 into the absorber 1 of the heat absorption tower. After absorbing solar energy, the salt is sent to the first storage tank 2. The hot salt flows from the first storage tank 2 through the molten salt superheater 3, evaporator 4, and liquid turbine 5 under gravity, and finally enters the cold salt tank. After the hot salt enters the liquid turbine 5, it drives the blades 502 to rotate and do work, releasing gravitational potential energy. At the same time, it transfers heat to the subcooled water through the blades 502, producing saturated water.

[0040] After being pressurized by the feedwater pump 9, the subcooled water enters the turbine 5 body through the cold water header 505, and exchanges heat with the molten salt through the turbine shaft 503 and blades 502 to become saturated water. The saturated water is collected from the hot water header 506 and enters the evaporator 4 to generate saturated steam. The saturated steam passes through the superheater 3 to generate superheated steam. The superheated steam enters the steam turbine 6 to do work and generate electricity. Then it is condensed into subcooled water through the condenser 8 and pressurized by the feedwater pump 9 to complete the water / steam cycle.

[0041] Example 2

[0042] The energy storage power generation system described in Example 1 is used to achieve peak shaving and valley filling.

[0043] The second day is predicted to be cloudy. During off-peak hours, cold salt is pumped into the first storage tank 2 by the cryogenic pump 11. During peak hours, the gravitational potential energy is converted into electrical energy by the hydraulic turbine 5 to achieve peak shaving and valley filling. At this time, only the hydraulic turbine 5 does the work of generating electricity.

[0044] If the next day is sunny, the electricity consumed by the cryogenic pump 11 can also come from off-peak electricity in the power grid. By absorbing off-peak electricity, the cold salt is stored in the first storage tank 2. During peak electricity consumption periods, the gravitational potential energy of the cold salt is converted into electrical energy by the hydraulic turbine 5, thus achieving peak shaving and valley filling.

[0045] Example 3

[0046] The energy storage and power generation system described in Example 1 is used to achieve the absorption of curtailed solar power.

[0047] If the forecast for the second day is sunny, during the midday period when solar power curtailment occurs, electricity consumption is relatively low. At this time, the solar thermal power plant's solar energy input is at its maximum, and the cryogenic pump 11 operates at full load, its power source being the curtailed solar energy. The cryogenic pump 11 transports cryogenic molten salt to the absorber 1 for heat absorption and temperature increase, and then stores it in a hot salt tank. During peak grid periods or when solar power load is low, the hot salt in the hot salt tank is released, generating electricity through the hydraulic turbine 5 and steam turbine 6, thus absorbing the curtailed solar energy and shaving off peak loads. During non-curtailment periods and when sunlight conditions are good, the electricity consumed by the cold salt pump comes from the solar thermal power plant's auxiliary power supply and is stored through the gravitational potential energy of the hot salt. During power generation, this gravitational potential energy is released through the hydraulic turbine 5, recovering the auxiliary power consumed by the cold salt pump.

[0048] The solar thermal energy storage power generation system provided in Example 1 can flexibly configure the ratio of input energy (waste solar power and solar energy) according to the actual operating conditions, increase the grid-connected power of the solar thermal power plant, and realize the absorption of curtailed solar power and peak shaving and valley filling.

[0049] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they shall still fall within the protection scope of the present invention.

Claims

1. A photo-thermal energy storage power generation system, characterized by, include: First storage tank, second storage tank, heat absorption tower, heat absorber, cryogenic pump and power generation system; The first storage tank is positioned higher than the second storage tank in the vertical direction. The heat absorber is installed on the heat absorption tower. The outlet of the second storage tank is connected to the inlet of the heat absorber and the inlet of the first storage tank through the cryogenic pump. The outlet of the heat absorber is connected to the inlet of the first storage tank. The outlet of the first storage tank is connected to the power generation system. The power generation system is used to convert the gravitational potential energy and thermal energy of the heat transfer medium in the first storage tank into electrical energy. The outlet of the heat transfer medium of the power generation system is connected to the inlet of the second storage tank. The power generation system includes a thermal power generation system, a potential power generation system, and a generator, with both the thermal power generation system and the potential power generation system connected to the generator; The thermal power generation system includes a superheater, an evaporator, a steam turbine, and a condenser; the potential energy power generation system includes a hydraulic turbine. The heat transfer medium in the first storage tank passes through the superheater and evaporator in sequence to exchange heat with the water in the thermal power generation system. The heat transfer medium in the evaporator enters the second storage tank via the liquid turbine. The water in the superheater passes through the steam turbine, condenser and evaporator in sequence to complete the circulation. The hydraulic turbine includes a hydraulic turbine body, which includes a hydraulic turbine shaft and blades. The blades are fixedly mounted on the hydraulic turbine shaft. The hydraulic turbine shaft and blades are provided with a channel communicating with a thermal power generation system. One end of the channel is connected to the condenser, and the other end is connected to the evaporator.

2. The solar thermal energy storage power generation system according to claim 1, characterized in that, The hydraulic turbine also includes a hot water manifold and a cold water manifold. The hot water header is connected to the inlet of the evaporator and is located between the turbine body and the generator. The turbine shaft and the generator shaft are connected inside the hot water header. The cold water header is connected to the condenser.

3. The solar thermal energy storage power generation system according to claim 2, characterized in that, A feedwater pump is also installed between the cold water header and the condenser.

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