Energy storage system based on water heat storage and organic Rankine cycle

Abstract

The invention provides an energy storage system based on water heat storage and organic Rankine cycle. The energy storage system comprises water heat storage equipment (1), a hot water circulating pump (3), a heat pump evaporator (4), throttling equipment (5), a compressor (8), a heat pump condenser (9), a heat storage and release working medium pump (17), a high-temperature working medium tank (18) and a low-temperature working medium tank (19). The heat supply sides of the water heat storage device (1), the hot water circulating pump (3) and the heat pump evaporator (4) are sequentially connected through pipelines to form a first loop. The heat absorption side of the heat pump evaporator (4), the compressor (8), the heat supply side of the heat pump condenser (9) and the throttling device (5) are sequentially connected through pipelines to form a second loop. According to the energy storage system, water heat storage, power grid residual electricity and the like can be converted into heat energy stored in the working medium in the high-temperature working medium tank through the organic Rankine cycle, the application range is wide, and the energy storage efficiency is high.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to an energy storage system based on water heat storage and an organic Rankine cycle. Technical Background

[0002] With the rapid development of the energy storage industry, energy storage technology has become a research hotspot today, and new technologies are emerging one after another. However, due to the limitations of economics and technical expertise, most energy storage application technologies are difficult to achieve large-scale application. At present, the most important energy storage technology is still pumped storage, accounting for 98% of the capacity. Although battery energy storage and compressed air energy storage technologies have developed rapidly in recent years, costs have also dropped rapidly, and projects ranging from tens to hundreds of megawatts have been continuously implemented, there are still many limitations.

[0003] Battery energy storage technology relies on the rapid development of the lithium battery industry. Driven by overcapacity, the cost has been greatly reduced. However, due to the relatively short life of lithium batteries and the high cost of handling scrapped batteries, the comprehensive cost of battery energy storage technology over its entire life cycle is still relatively high. However, the biggest constraint of this technology is the lack of safety of the battery. Whether in the manufacturing process or in actual operation, battery fire accidents are prone to occur.

[0004] There are currently many technical routes for compressed air energy storage, the mainstream of which are adiabatic and cryogenic liquefaction. Adiabatic compressed air energy storage replaces the traditional refueling process, does not consume fuel, and improves efficiency and economy, but gas storage usually requires a large underground space and is greatly restricted by the geographical environment. If high-pressure gas cylinders are used for gas storage, the cost is high and the energy storage density is low, which greatly limits its application. Cryogenic liquefied compressed air energy storage is to liquefy compressed air for storage, which solves the problems of limited space and high cost of high-pressure gas cylinders. However, due to the complexity of the cryogenic system and the high technical difficulty, the overall cost is still high, which restricts the further development of this technology.

[0005] Pumped storage has the advantages of low cost, high efficiency, and fast response. It is currently a very excellent energy storage technology, but there are also problems. On the one hand, it is restricted by geographical conditions. Especially in areas where wind and solar power are concentrated, they are often restricted by water resources or terrain and there is no suitable space. On the other hand, from a national perspective, excellent plant sites are gradually being developed, and the construction costs of subsequent projects are constantly increasing. At the same time, taking into account the rising costs of urban demolition and environmental protection, the cost of pumped storage has gradually increased from 1,000-2,000 yuan / kW in the early days to 3,000-4,000 yuan / kW. In the new projects started in 2018, the investment cost has reached 6,000-7,000 yuan / kW, and the cost is expected to continue to rise in the future.

[0006] Although existing technologies have various defects, the demand for energy storage is very urgent. Many projects now use battery energy storage with higher safety risks. How to develop efficient and safe energy storage technology has become a difficult problem that needs to be solved urgently in the industry. Summary of the invention

[0007] In view of this, the present invention provides an energy storage system based on water heat storage and organic Rankine cycle.

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0009] The energy storage system based on water heat storage and organic Rankine cycle according to the present invention comprises: a water heat storage device (1), a hot water circulation pump (3), a heat pump evaporator (4), a throttling device (5), a compressor (8), a heat pump condenser (9), a heat storage and release working fluid pump (17), a high-temperature working fluid tank (18) and a low-temperature working fluid tank (19), wherein:

[0010] The water heat storage device (1), the hot water circulation pump (3) and the heating side of the heat pump evaporator (4) are connected in sequence via pipelines to form a No. 1 loop;

[0011] The heat absorption side of the heat pump evaporator (4), the compressor (8), the heating side of the heat pump condenser (9) and the throttling device (5) are connected in sequence via pipelines to form a second loop;

[0012] The high-temperature working fluid tank (18), the heat absorption side of the heat pump condenser (9), the heat storage and release working fluid pump (17), and the low-temperature working fluid tank (19) are connected in sequence via pipelines.

[0013] Furthermore, the energy storage system based on water heat storage and organic Rankine cycle also includes a working fluid circulation pump (10), a turbine machine (11), an organic Rankine condenser (14), a heat exchanger (15) and an organic Rankine evaporator (16), wherein:

[0014] The water heat storage device (1), the hot water circulation pump (3) and the heat absorption side of the organic Rankine condenser (14) are connected in sequence via pipelines to form a third loop;

[0015] The heating side of the organic Rankine condenser (14), the working fluid circulation pump (10), the heat absorption side of the heat exchanger (15), the heat absorption side of the organic Rankine evaporator (16), the turbine machine (11) and the heating side of the heat exchanger (15) are connected in sequence via pipelines to form a fourth loop;

[0016] The high-temperature working fluid tank (18), the heat storage and release working fluid pump (17), the heating side of the organic Rankine evaporator (16), and the low-temperature working fluid tank (19) are connected in sequence via pipelines.

[0017] Furthermore, the energy storage system based on water heat storage and organic Rankine cycle also includes a solar thermal panel (2). The water heat storage device (1), the heating side of the heat pump evaporator (4), the hot water circulation pump (3) and the solar thermal panel (2) are sequentially connected via pipelines to form a fifth loop.

[0018] Furthermore, the water heat storage device (1), the hot water circulation pump (3), the heat absorption side of the organic Rankine condenser (14) and the solar thermal panel (2) are connected in sequence via pipelines to form a sixth loop.

[0019] Furthermore, the water heat storage device (1), the hot water circulation pump (3) and the solar thermal panel (2) are connected in sequence via pipelines to form a seventh loop.

[0020] Furthermore, the energy storage system based on water heat storage and organic Rankine cycle also includes an electric motor (6) for driving the compressor (8), and the electric motor (6) is connected to an external power supply (7).

[0021] Furthermore, the energy storage system based on water heat storage and organic Rankine cycle also includes a power generation device (12), the turbine machinery (11) drives the power generation device (12) to operate and generate electricity, and the power generation device (12) is connected to the power consumption device (13).

[0022] Furthermore, the working fluid in the heat pump evaporator (4) and the fourth loop is one of n-pentane R601, isopentane R601a, n-butane, R236ea, R236fa, R245ca, R245fa, isobutane and ammonia.

[0023] Furthermore, the working fluid in the high-temperature working fluid tank (18) and the low-temperature working fluid tank (19) is one of heat transfer oil, molten salt or phase change material.

[0024] Furthermore, a corresponding valve is provided in each of the pipelines.

[0025] The beneficial effects of the above technical solution of the present invention are as follows:

[0026] According to the energy storage system based on water heat storage and organic Rankine cycle in the embodiment of the present invention, heat energy is stored by using water heat storage equipment, and then this part of heat energy and surplus electricity of the power grid are jointly provided to the working process of the organic Rankine cycle, so that the surplus electricity is efficiently stored in the high-temperature working fluid tank. At the same time, the energy storage process utilizes renewable energy such as solar energy to achieve clean energy storage. In addition, the energy storage system also has the characteristics of realizing energy storage and power generation under various working conditions, is suitable for various load conditions, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of the system composition of an energy storage system based on water heat storage and organic Rankine cycle according to an embodiment of the present invention;

[0028] Figure 2 It is a schematic diagram of an energy storage system based on water heat storage and organic Rankine cycle in working condition No. 1 according to an embodiment of the present invention;

[0029] Figure 3 It is a schematic diagram of an energy storage system based on water heat storage and organic Rankine cycle in working condition No. 2 according to an embodiment of the present invention;

[0030] Figure 4 It is a schematic diagram of an energy storage system based on water heat storage and organic Rankine cycle in working condition No. 3 according to an embodiment of the present invention;

[0031] Figure 5 It is a schematic diagram of an energy storage system based on water heat storage and organic Rankine cycle in working condition No. 4 according to an embodiment of the present invention;

[0032] Figure 6 It is a schematic diagram of an energy storage system based on water heat storage and organic Rankine cycle in working condition No. 5 according to an embodiment of the present invention;

[0033] Reference numerals:

[0034] Water heat storage equipment 1, solar thermal panel 2, hot water circulation pump 3, heat pump evaporator 4, throttling device 5, motor 6, external power supply 7, compressor 8, heat pump condenser 9, working fluid circulation pump 10, turbine machinery 11, power generation equipment 12, electrical equipment 13, organic Rankine condenser 14, heat exchanger 15, organic Rankine evaporator 16, heat storage and release working fluid pump 17, high temperature working fluid tank 18, low temperature working fluid tank 19. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0036] like Figure 3 As shown, the energy storage system based on water heat storage and organic Rankine cycle in this embodiment includes a water heat storage device 1, a hot water circulation pump 3, a heat pump evaporator 4, a throttling device 5, a compressor 8, a heat pump condenser 9, a heat storage and release working fluid pump 17, a high-temperature working fluid tank 18 and a low-temperature working fluid tank 19.

[0037] Among them, the water heat storage device 1, the hot water circulation pump 3 and the heating side of the heat pump evaporator 4 are connected in sequence through pipelines to form a No. 1 loop; the heat absorption side of the heat pump evaporator 4, the compressor 8, the heating side of the heat pump condenser 9 and the throttling device 5 are connected in sequence through pipelines to form a No. 2 loop. The high-temperature working fluid tank 18, the heat absorption side of the heat pump condenser 9, the heat storage and release working fluid pump 17, and the low-temperature working fluid tank 19 are connected in sequence through pipelines.

[0038] In loop No. 1, the high-temperature water in the upper layer of the water heat storage device 1 flows into the heating side of the heat pump evaporator 4 driven by the hot water circulation pump 3, and exchanges heat with the low-temperature and low-pressure working medium on its heat absorption side in the heat pump evaporator 4. The working medium on the heat absorption side absorbs heat from the low-temperature and low-pressure liquid state and boils and transforms into a high-temperature and low-pressure gas state, while the high-temperature water releases most of its heat and becomes low-temperature water, and returns to the water heat storage device 1 along the pipeline.

[0039] Since the density of water decreases with increasing temperature when the temperature is above 4 degrees Celsius, the density of the upper water layer is less than that of the lower water layer. Under the effect of the density difference, the water in the water heat storage device 1 will be stratified, and the junction of the high-temperature water and the low-temperature water becomes a thermocline layer. Because the thermal conductivity of water is low, there is no obvious heat convection in the device. Therefore, the thermocline layer can separate the high-temperature water and the low-temperature water in the water heat storage device 1 and play an insulating role. In this way, high-temperature water and low-temperature water can exist in the water heat storage device 1 at the same time, that is, the high-temperature water is located in the upper layer of the water heat storage device 1, and the low-temperature water is located in the lower layer of the water heat storage device 1.

[0040] In the second loop, the heat-absorbing side working medium flowing into the heat pump evaporator 4 absorbs the heat transferred by the high-temperature water and becomes a high-temperature, low-pressure gas, and then flows into the compressor 8 for compression. The working medium is compressed from a high-temperature, low-pressure gas state to a high-temperature, high-pressure gas state. The high-temperature, high-pressure gas enters the heating side of the heat pump condenser 9, and exchanges heat with the heat storage working medium on the heat-absorbing side in the heat pump condenser 9. After releasing most of the heat, the high-temperature, high-pressure gas is cooled to a low-temperature, high-pressure liquid or a low-temperature, high-pressure gas-liquid mixture, and then enters the throttling device 5. The throttling device 5 includes but is not limited to throttling devices such as throttling valves and expansion valves. It mainly plays a throttling role, reducing the pressure of the low-temperature, high-pressure liquid or the high-temperature, low-pressure gas-liquid mixture working medium, so that the working medium is changed back to a low-temperature, low-pressure liquid state under a low-temperature, high-pressure state. The throttling device 5 is an important component for maintaining the working medium in the heat pump condenser 9 at a high pressure and the working medium in the heat pump evaporator 4 at a low pressure. The low-temperature, low-pressure liquid working medium that has returned to its initial state enters the heat pump evaporator 4 again for the next cycle.

[0041] The heat storage medium in the low-temperature working medium tank 19 is continuously sent out by the heat storage and release working medium pump 17, enters the heat absorption side of the heat pump condenser 9 to obtain heat, increases its own temperature, and then flows to the high-temperature working medium tank and is stored therein, thereby realizing energy storage.

[0042] In this embodiment, the compressor 8 is connected and driven by the motor 6, and the working power of the motor 6 is provided by the external power supply 7. The external power supply 7 can be renewable energy such as wind power and photovoltaic power to absorb its electrical energy, or it can be grid power to store excess electrical energy to achieve the purpose of peak shaving and valley filling.

[0043] like Figure 1 As shown, further, the energy storage system based on water heat storage and organic Rankine cycle in this embodiment also includes a solar thermal panel 2, and the water heat storage device 1, the heating side of the heat pump evaporator 4, the hot water circulation pump 3 and the solar thermal panel 2 are connected in sequence through pipelines to form a fifth loop.

[0044] In the No. 5 loop, the high-temperature water in the upper layer of the water heat storage device 1 enters the solar thermal panel 2 under the action of the hot water circulation pump 3. After absorbing the solar heat, the high-temperature water increases in temperature and then flows into the heating side of the heat pump evaporator 4 to exchange heat with the low-temperature and low-pressure working medium on its heat absorption side. By supplementing the high-temperature water in the water heat storage device 1 with solar energy, the storage efficiency of the energy storage system can be improved, and the amount of high-temperature water in the upper layer of the water heat storage device 1 can also be saved.

[0045] like Figure 1 As shown, further, the energy storage system based on water heat storage and organic Rankine cycle in this embodiment also includes a working fluid circulation pump 10 , a turbine machine 11 , an organic Rankine condenser 14 , a heat exchanger 15 and an organic Rankine evaporator 16 .

[0046] Among them, the water heat storage device 1, the hot water circulation pump 3 and the heat absorption side of the organic Rankine condenser 14 are connected in sequence through pipelines to form a No. 3 loop; the heating side of the organic Rankine condenser 14, the working fluid circulation pump 10, the heat absorption side of the heat exchanger 15, the heat absorption side of the organic Rankine evaporator 16, the turbine machinery 11 and the heating side of the heat exchanger 15 are connected in sequence through pipelines to form a No. 4 loop; the high-temperature working fluid tank 18, the heat storage and release working fluid pump 17, the heating side of the organic Rankine evaporator 16, and the low-temperature working fluid tank 19 are connected in sequence through pipelines.

[0047] Under the action of the heat storage and release working fluid pump 17, the high-temperature energy storage working fluid in the high-temperature working fluid tank 18 flows out and enters the heating side of the organic Rankine evaporator 16, heats the low-temperature working fluid on the heat absorption side of the organic Rankine evaporator 16, and returns to the low-temperature working fluid tank 19 along the pipeline after losing most of its heat.

[0048] In the fourth circuit, the low-temperature working fluid on the heat absorption side of the organic Rankine evaporator 16 is heated after absorbing the heat transferred by the high-temperature energy storage working fluid, and continues to absorb heat until it reaches a saturated or overheated state, and then expands in volume and flows into the turbine machine 11. The turbine machine 11 converts the thermal energy in the working fluid into mechanical energy. The turbine machine 11 is connected to the power generation equipment 12, so that the turbine machine 11 works on the power generation equipment 12, and the power generation equipment 12 converts the mechanical energy into electrical energy and transmits it to the electrical equipment 13 for supply to users. The working fluid flows out of the turbine machine 11. After the working medium comes, it still has a high heat. When the working medium enters the heating side of the heat exchanger 15, part of the heat is transferred to the heat absorption side of the heat exchanger 15, and then continues to flow into the heating side of the organic Rankine condenser 14, and again transfers the excess heat to the heat absorption side of the organic Rankine condenser 14. At this time, the working medium becomes liquid due to heat release, and the liquid working medium enters the working medium circulation pump 10 and enters the heat absorption side of the heat exchanger 15 after being pressurized. After preliminary heating through heat transfer, it flows into the heat absorption side of the organic Rankine evaporator 16 again to carry out the next cycle.

[0049] In the No. 3 loop, the low-temperature water in the lower layer of the water heat storage device 1 flows into the heat absorption side of the organic Rankine condenser 14 under the action of the hot water circulation pump 3, absorbs the heat on the heating side of the organic Rankine condenser 14, becomes high-temperature water, and then returns to the upper layer of the water heat storage device 1 along the pipeline. Since the density of the high-temperature water entering the upper layer of the water heat storage device 1 is lower than that of the low-temperature water in the lower layer of the water heat storage device 1, the water in the high-temperature state will be stored in the upper layer of the water heat storage device 1 due to the density difference.

[0050] According to the energy storage system of this embodiment, excess energy can be conveniently and efficiently stored in the high-temperature working fluid tank 18. At the same time, the heat stored in the high-temperature working fluid tank 18 can also be conveniently and efficiently used to generate electricity through an organic Rankine cycle for use by electrical equipment. At the same time, the remaining heat of the working fluid after power generation can also be stored through the water heat storage device 1 to achieve efficient utilization.

[0051] like Figure 3 As shown, further, the water heat storage device 1, the hot water circulation pump 3, the heat absorption side of the organic Rankine condenser 14 and the solar thermal panel 2 are connected in sequence through pipelines to form a sixth loop.

[0052] In the sixth loop, the low-temperature water in the lower layer of the water thermal storage device 1 flows to the heat absorption side of the organic Rankine condenser 14 under the action of the hot water circulation pump 3, absorbs the heat from the heating side of the organic Rankine condenser 14, becomes high-temperature water and enters the solar thermal panel 2, absorbs the heat of the solar energy and continues to heat up, and then returns to the upper layer of the water thermal storage device 1 along the pipeline after secondary heating. Since the density of the high-temperature water entering the upper layer of the water thermal storage device 1 is lower than the low-temperature water in the lower layer of the water thermal storage device 1, the water in the high-temperature state will be stored in the upper layer of the water thermal storage device 1 due to the density difference. The addition of the solar thermal panel 2 can ensure that the water temperature in the upper layer of the water thermal storage device 1 is always at a higher temperature, thereby ensuring the overall thermal efficiency of the energy storage system.

[0053] like Figure 3 As shown, further, the water heat storage device 1, the hot water circulation pump 3 and the solar thermal panel 2 are connected in sequence through pipelines to form a seventh loop.

[0054] In the seventh loop, the low-temperature water in the lower layer of the water heat storage device 1 flows into the solar thermal panel 2 under the action of the hot water circulation pump 3, absorbs the heat of the solar energy and continues to heat up before returning to the upper layer of the water heat storage device 1 along the pipeline. Since the density of the high-temperature water entering the upper layer of the water heat storage device 1 is lower than the low-temperature water in the lower layer of the water heat storage device 1, the water in the high-temperature state will be stored in the upper layer of the water heat storage device 1 under the action of the density difference. The high-temperature water in the upper layer of the water heat storage device 1 can be used as the heat source of the heat pump evaporator 4, and the low-temperature water in the lower layer of the water heat storage device 1 can be used as the cold source of the organic Rankine condenser 14. The water heat storage technology adopted in this embodiment has many advantages such as low cost, high efficiency and fast response.

[0055] The working fluid in the heat pump evaporator 4 and the fourth circuit in this embodiment can be a high-temperature organic working fluid such as n-pentane R601, isopentane R601a, R245ca, or a high-temperature organic working fluid with similar physical and chemical properties, or a medium-temperature organic working fluid such as R245fa, n-butane, R236ea, R236fa, isobutane, or a medium-temperature organic working fluid with similar physical and chemical properties, or an inorganic working fluid in a similar temperature range such as ammonia. Specifically, the working fluid in the heat pump evaporator 4 and the fourth circuit in this embodiment can be selected from one of n-pentane R601, isopentane R601a, n-butane, R236ea, R236fa, R245ca, R245fa, isobutane and ammonia, or two or more working fluids in a similar temperature range and can be mixed.

[0056] Furthermore, the working fluid in the high-temperature working fluid tank 18 and the low-temperature working fluid tank 19 in this embodiment is one of heat transfer oil, molten salt or phase change material, and the above working fluid has the advantages of high energy storage density and high energy storage efficiency.

[0057] Furthermore, valves are provided in the pipelines in this embodiment so that different pipelines and equipment can form different circuits by controlling the opening and closing of different valves, so that the energy storage system can quickly switch between different working conditions, achieving intelligent, flexible, efficient and environmentally friendly effects.

[0058] This embodiment further divides the operating conditions of the energy storage system based on water heat storage and organic Rankine cycle into the following five types.

[0059] Working condition No. 1:

[0060] like Figure 2 As shown, the first working condition is the starting working condition, and the solar thermal panel 2 is used to store heat for the water heat storage device 1. Under this working condition, the initial water temperature in the water heat storage device 1 is room temperature (about 20°C, about 5°C in winter). During the energy storage process, the solar thermal panel 2 absorbs solar energy, and the room temperature water in the lower layer of the water heat storage device 1 is heated to the high temperature zone (70-95°C) by the solar thermal panel 2 under the action of the hot water circulation pump 3. After the temperature rises, it returns to the upper layer of the water heat storage device 1. Since the upper layer water temperature is higher and the lower layer water temperature is lower, under the action of the density difference, the water in the water heat storage device 1 will produce a temperature oblique layer, and high-temperature water and low-temperature water can exist in the water heat storage device 1 at the same time. After the entire energy storage system is started for the first time or shut down for a period of time, the energy storage system needs to run this working condition first and use the water heat storage device 1 for initial heat storage.

[0061] Working condition No. 2:

[0062] like Figure 3 As shown, the second working condition is the electricity storage working condition, and the heat energy in the water heat storage device 1 and the excess electric energy such as the surplus power of the power grid are stored in the high-temperature working medium tank 18 through the organic Rankine cycle. Under this working condition, the high-temperature water in the upper layer of the water heat storage device 1 is heat-exchanged with the low-temperature and low-pressure liquid working medium therein through the heat pump evaporator 4 under the action of the hot water circulation pump 3, so that the low-temperature and low-pressure liquid working medium absorbs heat and boils and is converted into a high-temperature and low-pressure gaseous working medium. At this time, the external power supply 7 is connected to drive the motor 6 and then the compressor 8 to compress the high-temperature and low-pressure gaseous working medium in the heat pump evaporator 4. After compression, the working medium becomes a high-temperature and high-pressure gaseous state, and then enters the heat pump condenser 9. The high-temperature and high-pressure gaseous working medium releases heat and transfers the heat to the heat storage working medium. The heat storage working medium flows out from the low-temperature working medium tank 19 under the action of the heat storage and release working medium pump 17, and the temperature rises after passing through the heat pump condenser 9, and then flows to the high-temperature working medium tank 18, completing the conversion of electric energy to thermal energy and realizing storage.

[0063] Working condition No.3:

[0064] like Figure 4As shown, the third working condition is the electricity storage working condition with solar energy supplementation. The heat energy in the water heat storage device 1 and the excess electric energy such as the surplus power of the power grid are stored in the high-temperature working medium tank 18 through the organic Rankine cycle. In addition, the solar thermal panel 2 also supplements the water in the water heat storage device 1. This working condition is suitable for the case where the solar energy conditions are good. Under this working condition, the water temperature of the upper layer of the water heat storage device 1 is in the high temperature zone (70-95°C). Due to the continuous heat dissipation, its temperature will drop over time, and the lower temperature zone will still remain in the low temperature zone (10°C-40°C). At this time, the high-temperature water in the upper layer of the water heat storage device 1 enters the solar thermal panel 2 under the action of the hot water circulation pump 3. After absorbing solar energy, the temperature rises and then enters the heat pump evaporator 4 to exchange heat with the low-temperature and low-pressure liquid working medium therein. The subsequent working process is the same as the above-mentioned working condition No. 2. By using the solar thermal panel 2 to supplement the water heat storage device 1 as the heat source of the heat pump evaporator 4 during the energy storage process, the storage efficiency can be increased and the use of hot water in the water heat storage device 1 can be saved.

[0065] Working condition No. 4:

[0066] like Figure 5 As shown, the fourth working condition is the discharge working condition with solar heat supplement, and the heat energy stored in the high-temperature working medium tank 18 is used to generate electricity for the electrical equipment through the organic Rankine cycle. This working condition is suitable for the case where the solar energy conditions are good. Under this working condition, the high-temperature working medium in the high-temperature working medium tank 18 flows into the organic Rankine evaporator 16 under the action of the heat storage and release working medium pump 17, and heats the low-temperature and low-pressure liquid working medium therein, and then returns to the low-temperature working medium tank 19. After being heated and boiled, the low-temperature and low-pressure liquid working medium continues to absorb heat until it reaches a saturated or overheated state, expands in volume, and drives the turbine machinery 11 to do work on the power generation equipment 12. The power generation equipment 12 converts mechanical energy into electrical energy to generate electricity, and supplies the electrical energy to the electrical equipment. The low-temperature water in the lower layer of the water heat storage device 1 exchanges heat with the gaseous working medium in the organic Rankine condenser 14 under the action of the hot water circulation pump 3 and heats up to a high temperature zone, then enters the solar thermal panel 2 to absorb solar energy and continue to heat up, and then returns to the upper layer of the water heat storage device 1, thereby storing the remaining heat after power generation. The addition of the solar thermal panel 2 can ensure the water temperature of the upper layer of the water heat storage device 1 and ensure the overall thermal efficiency of the energy storage system.

[0067] Working condition No. 5:

[0068] like Figure 6As shown, the fifth working condition is the discharge working condition without solar heat supplement, and the heat energy stored in the high-temperature working fluid tank 18 is used to generate electricity for the electrical equipment through the organic Rankine cycle. This working condition is suitable for the case where the solar energy conditions are not good. Under this working condition, the high-temperature working fluid in the high-temperature working fluid tank 18 flows into the organic Rankine evaporator 16 under the action of the heat storage and release working fluid pump 17, and heats the low-temperature and low-pressure liquid working fluid therein, and then returns to the low-temperature working fluid tank 19. After being heated and boiled, the low-temperature and low-pressure liquid working fluid continues to absorb heat until it reaches a saturated or overheated state, expands in volume, and drives the turbine machinery 11 to work on the power generation equipment 12. The power generation equipment 12 converts mechanical energy into electrical energy to generate electricity, and supplies electrical energy to the electrical equipment. The low-temperature water in the lower layer of the water heat storage device 1 exchanges heat with the gaseous working fluid in the organic Rankine condenser 14 under the action of the hot water circulation pump 3 to heat up to the high temperature zone, and then returns to the upper layer of the water heat storage device 1, thereby storing the remaining heat after power generation.

[0069] As mentioned above, the above five working conditions can be quickly switched between the above five working conditions by controlling the opening and closing of different valves so that different pipelines and equipment form different circuits.

[0070] The above is a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements can be made without departing from the principles of the present invention, and these improvements should also be regarded as the scope of protection of the present invention.

Claims

1. An energy storage system based on water heat storage and organic Rankine cycle, characterized in that: include: Water heat storage equipment (1), hot water circulation pump (3), heat pump evaporator (4), throttling equipment (5), compressor (8), heat pump condenser (9), heat storage and release working fluid pump (17), high temperature working fluid tank (18) and low temperature working fluid tank (19), wherein: The water heat storage device (1), the hot water circulation pump (3) and the heating side of the heat pump evaporator (4) are connected in sequence via pipelines to form a No. 1 loop; The heat absorption side of the heat pump evaporator (4), the compressor (8), the heating side of the heat pump condenser (9) and the throttling device (5) are connected in sequence via pipelines to form a second loop; The high-temperature working fluid tank (18), the heat absorption side of the heat pump condenser (9), the heat storage and release working fluid pump (17), and the low-temperature working fluid tank (19) are connected in sequence via pipelines.

2. The energy storage system based on water heat storage and organic Rankine cycle according to claim 1, characterized in that: It also includes a working fluid circulation pump (10), a turbine machine (11), an organic Rankine condenser (14), a heat exchanger (15) and an organic Rankine evaporator (16), wherein: The water heat storage device (1), the hot water circulation pump (3) and the heat absorption side of the organic Rankine condenser (14) are connected in sequence via pipelines to form a third loop; The heating side of the organic Rankine condenser (14), the working fluid circulation pump (10), the heat absorption side of the heat exchanger (15), the heat absorption side of the organic Rankine evaporator (16), the turbine machine (11) and the heating side of the heat exchanger (15) are connected in sequence via pipelines to form a fourth loop; The high-temperature working fluid tank (18), the heat storage and release working fluid pump (17), the heating side of the organic Rankine evaporator (16), and the low-temperature working fluid tank (19) are connected in sequence via pipelines.

3. The energy storage system based on water heat storage and organic Rankine cycle according to claim 1, characterized in that: The water heat storage device (1), the heating side of the heat pump evaporator (4), the hot water circulation pump (3) and the solar heat panel (2) are connected in sequence through pipelines to form a fifth loop.

4. The energy storage system based on water heat storage and organic Rankine cycle according to claim 3, characterized in that: The water heat storage device (1), the hot water circulation pump (3), the heat absorption side of the organic Rankine condenser (14) and the solar thermal panel (2) are connected in sequence via pipelines to form a sixth loop.

5. The energy storage system based on water heat storage and organic Rankine cycle according to claim 3, characterized in that: The water heat storage device (1), the hot water circulation pump (3) and the solar thermal panel (2) are connected in sequence via pipelines to form a seventh loop.

6. The energy storage system based on water heat storage and organic Rankine cycle according to claim 1, characterized in that: It also includes an electric motor (6) for driving the compressor (8), and the electric motor (6) is connected to an external power source (7).

7. The energy storage system based on water heat storage and organic Rankine cycle according to claim 2, characterized in that: It also includes a power generation device (12), wherein the turbine machinery (11) drives the power generation device (12) to generate electricity, and the power generation device (12) is connected to an electrical device (13).

8. The energy storage system based on water heat storage and organic Rankine cycle according to claim 2, characterized in that: The working fluid in the heat pump evaporator (4) and the fourth loop is one of n-pentane R601, isopentane R601a, n-butane, R236ea, R236fa, R245ca, R245fa, isobutane and ammonia.

9. The energy storage system based on water heat storage and organic Rankine cycle according to claim 1, characterized in that: The working fluid in the high-temperature working fluid tank (18) and the low-temperature working fluid tank (19) is one of heat transfer oil, molten salt or phase change material.

10. An energy storage system based on water heat storage and organic Rankine cycle according to any one of claims 1 to 9, characterized in that: Corresponding valves are arranged in each of the pipelines.

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