A water vapor energy storage system with cascade thermal storage and a control method thereof

Abstract

The present invention discloses a water vapor energy storage system with cascade thermal storage and a control method. The system includes a first evaporator, a first compressor, an intercooler, a second compressor, a precooler, a second condenser, an aftercooler, a waste heat exchanger, a throttle valve, a pump, a preheater, a second evaporator, a superheater, a first turbine, a reheater, a second turbine, a first condenser, a first cold storage tank, a first heat storage tank, a second cold storage tank, a second heat storage tank, a third cold storage tank, a third heat storage tank, a fourth cold storage tank, and a fourth heat storage tank. The method avoids the problem of needing to set up separate storage tanks to store working fluids in the traditional system by designing the energy storage and energy release processes as closed loops. The method can flexibly adapt to different application scenarios, is not restricted by terrain, and realizes wide-area energy supply. The energy storage process and energy release process of the present invention are respectively completed by two closed loops, and there is no need to set up separate storage tanks to store working fluids, thereby reducing system construction costs.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage technology, and in particular relates to a water vapor energy storage system with cascade thermal storage and a control method. Background Art

[0002] Energy storage technology has the function of shaving peaks and filling valleys, which can reduce the impact of renewable energy generation on the power grid, improve the stability of the power grid, and can be widely used in power industry production.

[0003] Currently, traditional energy storage technologies include pumped hydro, compressed gas storage, and electrochemical storage. Pumped hydro is subject to unique topographical conditions, while compressed gas storage typically requires large, high-pressure tanks to store the working fluid, limiting its use in certain environments. Electrochemical storage also has drawbacks such as low safety and environmental pollution. Summary of the Invention

[0004] The present invention aims to provide a water vapor energy storage system and control method with cascaded thermal storage to address the aforementioned technical problems. By designing the energy storage and release processes as closed loops, the energy storage system of the present invention avoids the need for separate tanks to store the working fluids used in these processes in traditional systems. This system can flexibly adapt to different application scenarios, is not restricted by terrain, and enables wide-area energy supply.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A water vapor energy storage system with cascade thermal storage includes a first evaporator, a first compressor, an intercooler, a second compressor, a precooler, a second condenser, an aftercooler, a waste heat exchanger, a throttle valve, a pump, a preheater, a second evaporator, a superheater, a first turbine, a reheater, a second turbine, a first condenser, a first cold storage tank, a first heat storage tank, a second cold storage tank, a second heat storage tank, a third cold storage tank, a third heat storage tank, a fourth cold storage tank, and a fourth heat storage tank;

[0007] The first outlet of the first evaporator is connected to the inlet of the first compressor, the outlet of the first compressor is connected to the first inlet of the intercooler, the first outlet of the intercooler is connected to the inlet of the second compressor, the outlet of the second compressor is connected to the first inlet of the precooler, the first outlet of the precooler is connected to the first inlet of the second condenser, the first outlet of the second condenser is connected to the first inlet of the aftercooler, the first outlet of the aftercooler is divided into two paths after passing through the throttle valve, one path is connected to the first inlet of the first evaporator, and the other path is connected to the inlet of the waste heat exchanger, and the outlet of the waste heat exchanger merges with the first outlet of the intercooler and is connected to the inlet of the second compressor;

[0008] The first outlet of the first condenser is connected to the pump inlet, the pump outlet is connected to the first inlet of the preheater, the first outlet of the preheater is connected to the first inlet of the second evaporator, the first outlet of the second evaporator is connected to the first inlet of the superheater, the first outlet of the superheater is connected to the inlet of the first turbine, the outlet of the first turbine is divided into two paths, one path is connected to the first inlet of the reheater, the first outlet of the reheater is connected to the inlet of the second turbine, the outlet of the second turbine is connected to the first inlet of the first condenser, and the other path is connected to the first inlet of the first condenser;

[0009] The first cold storage tank is connected to the second inlet of the aftercooler, the second outlet of the aftercooler is connected to the inlet of the first heat storage tank, the outlet of the first heat storage tank is connected to the second inlet of the preheater, and the second outlet of the preheater is connected to the inlet of the first cold storage tank;

[0010] The second cold storage tank is connected to the second inlet of the second condenser, and the second outlet of the second condenser is divided into two routes, one route is connected to the inlet of the second heat storage tank, the outlet of the second heat storage tank is connected to the second inlet of the second evaporator, the second outlet of the second evaporator is connected to the inlet of the second cold storage tank, and the other route is connected to the second inlet of the precooler, and the second outlet of the precooler is connected to the inlet of the third heat storage tank; the outlet of the third heat storage tank is connected to the second inlet of the superheater, and the second outlet of the superheater is divided into two routes, one route is connected to the second inlet of the second evaporator, and the other route is connected to the inlet of the third cold storage tank, and the outlet of the third cold storage tank is connected to the second inlet of the precooler;

[0011] The fourth cold storage tank outlet is connected to the second inlet of the intercooler, the second outlet of the intercooler is connected to the inlet of the fourth heat storage tank, the fourth heat storage tank outlet is connected to the second inlet of the reheater, and the second outlet of the reheater is connected to the inlet of the fourth cold storage tank;

[0012] The second inlet of the first evaporator is a heat source, which provides heat for the evaporation of the working medium in the first evaporator 1;

[0013] The second inlet of the first condenser is a cold source, which provides cold energy for the condensation of the working medium in the first condenser.

[0014] A further improvement of the present invention is that it further includes a first control valve, a second control valve, a third control valve, a fourth control valve, a fifth control valve, a sixth control valve, a seventh control valve, an eighth control valve, a ninth control valve, a tenth control valve, an eleventh control valve, a twelfth control valve, a thirteenth control valve, a fourteenth control valve, a fifteenth control valve, a sixteenth control valve, a seventeenth control valve, an eighteenth control valve, a nineteenth control valve, a twentieth control valve, and a twenty-first control valve;

[0015] The first outlet of the first evaporator is connected to the inlet of the first compressor through the first control valve, the first outlet of the intercooler is connected to the inlet of the second compressor through the fifth control valve, the first outlet of the aftercooler is divided into two paths after passing through the throttle valve, one path is connected to the first inlet of the first evaporator through the third control valve, and the other path is connected to the inlet of the waste heat exchanger through the second control valve. The outlet of the waste heat exchanger is connected to the first outlet of the intercooler through the twenty-first control valve and connected to the inlet of the second compressor;

[0016] The first outlet of the first condenser is connected to the pump inlet via the thirteenth control valve; the first turbine outlet is split into two routes: one route is connected to the first inlet of the reheater via the fourteenth control valve, the first outlet of the reheater is connected to the second turbine inlet, the second turbine outlet is connected to the first inlet of the first condenser via the twelfth control valve, and the other route is connected to the first inlet of the first condenser via the fifteenth control valve.

[0017] The first cold storage tank is connected to the second inlet of the aftercooler through the seventh control valve, and the outlet of the first heat storage tank is connected to the second inlet of the preheater through the 20th control valve;

[0018] The second cold storage tank is connected to the second inlet of the second condenser through the eighth control valve. The second outlet of the second condenser is divided into two routes, one of which is connected to the inlet of the second heat storage tank through the ninth control valve. The outlet of the second heat storage tank is connected to the second inlet of the second evaporator through the nineteenth control valve, and the other route is connected to the second inlet of the precooler through the sixth control valve. The second outlet of the precooler is connected to the inlet of the third heat storage tank; the outlet of the third heat storage tank is connected to the second inlet of the superheater through the sixteenth control valve. The second outlet of the superheater is divided into two routes, one of which is connected to the second inlet of the second evaporator through the eighteenth control valve, and the other route is connected to the inlet of the third cold storage tank through the seventeenth control valve. The outlet of the third cold storage tank passes through the tenth control valve and the sixth control valve and then merges to connect to the second inlet of the precooler;

[0019] The outlet of the fourth cold storage tank is connected to the second inlet of the intercooler through the fourth control valve, and the outlet of the fourth heat storage tank is connected to the second inlet of the reheater through the eleventh control valve.

[0020] A further improvement of the present invention is that the energy storage process and the energy release process of the system are independent closed loops.

[0021] A further improvement of the present invention is that the working fluid used in the energy storage circuit, the energy release circuit and the multiple cascade heat storage circuits is water;

[0022] The energy storage circuit consists of the first evaporator, the first compressor, the intercooler, the second compressor, the precooler, the second condenser, the aftercooler, the throttle valve, the waste heat heater, the first control valve, the second control valve, the third control valve, the fifth control valve, the sixth control valve and the twenty-first control valve; the energy release circuit consists of the first condenser, the pump, the preheater, the second evaporator, the superheater, the first turbine, the reheater, the second turbine, the twelfth control valve, the thirteenth control valve, the fourteenth control valve, the fifteenth control valve and the eighteenth control valve; the cascade heat storage circuit consists of the first cold storage tank, the first heat storage tank, the second cold storage tank, the second heat storage tank, the third cold storage tank, the third heat storage tank, the fourth cold storage tank, the fourth heat storage tank, the fourth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve, the eleventh control valve, the sixteenth control valve, the seventeenth control valve, the nineteenth control valve and the twentieth control valve.

[0023] A further improvement of the present invention is that the system adopts a stepped arrangement of multiple storage tanks to achieve stepped energy utilization and improve energy utilization rate.

[0024] A further improvement of the present invention is that a second condenser and a second evaporator are used in the cascade heat storage, and a large amount of latent heat released by the working medium water during the phase change process is utilized to improve the heat storage capacity of the system.

[0025] A further improvement of the present invention is that when waste heat exists, a waste heat exchanger is put into use to recover the waste heat, increase the heat storage temperature of the third heat storage tank, and thus increase the working capacity of the working medium at the first turbine inlet.

[0026] A further improvement of the present invention is that when the system is applied to a place with a stable supply of waste heat, the first-stage compressor, the first evaporator, the intercooler, the fourth cold storage tank, the fourth heat storage tank, the reheater and the second turbine are eliminated.

[0027] A control method for a water vapor energy storage system with cascade thermal storage, comprising:

[0028] In the initial state, all twenty-one control valves are closed and the system is in shutdown state;

[0029] When the user is in the off-peak period of electricity consumption, the second control valve, the tenth control valve, the eleventh control valve, the twelfth control valve, the thirteenth control valve, the fourteenth control valve, the fifteenth control valve, the sixteenth control valve, the seventeenth control valve, the eighteenth control valve, the nineteenth control valve, the twentieth control valve and the twenty-first control valve are closed, and the first control valve, the third control valve, the fourth control valve, the fifth control valve, the sixth control valve, the seventh control valve, the eighth control valve and the ninth control valve are opened, and the energy storage part of the cascade heat storage water vapor energy storage system works; the water vapor generated by the first evaporator flows out from the first outlet of the first evaporator, passes through the first control valve and enters the first compressor for pressure boosting, and then flows into the intercooler to transfer heat to the low-temperature heat storage medium flowing out of the fourth cold storage tank, and then flows into the second compressor to boost the pressure to a high temperature and high pressure state again, and the working medium flows into the precooler to transfer heat to the low-temperature heat storage medium flowing out of the second outlet of the second condenser The heat storage medium then enters the second condenser to transfer heat to the heat storage medium flowing out of the second cold storage tank. The working medium releases a large amount of latent heat and condenses to a saturated water state. It then passes through the aftercooler to transfer heat to the low-temperature heat storage medium flowing out of the first cold storage tank. The working medium is cooled to a supercooled water state and finally returns to the first evaporator after throttling and expansion by the throttle valve. It exchanges heat with the heat source and evaporates into a gaseous state and continues to circulate; the low-temperature heat storage medium at the outlet of the first cold storage tank passes through the seventh control valve and absorbs heat in the aftercooler before entering the first heat storage tank for storage; the heat storage medium in the second cold storage tank passes through the eighth control valve and absorbs heat in the second condenser, and then is divided into two paths, one path passes through the ninth control valve and enters the second heat storage tank for storage, and the other path passes through the sixth control valve and enters the precooler to absorb heat, and then enters the third heat storage tank for storage; the low-temperature heat storage medium in the fourth cold storage tank passes through the fourth control valve and absorbs heat in the intercooler, and then enters the fourth heat storage tank for storage;

[0030] When the user is at the peak of electricity consumption, the first control valve, the second control valve, the third control valve, the fourth control valve, the fifth control valve, the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve, the fifteenth control valve, the seventeenth control valve and the twenty-first control valve are closed, and the eleventh control valve, the twelfth control valve, the thirteenth control valve, the fourteenth control valve, the sixteenth control valve, the eighteenth control valve, the nineteenth control valve and the twenty-first control valve are opened, and the energy release part of the cascade heat storage water vapor energy storage system starts to work; low-temperature and low-pressure liquid water flows out of the first condenser, passes through the thirteenth control valve and enters the pump, and after the working fluid is pressurized, it enters the preheater to absorb the heat of the high-temperature heat storage medium flowing out of the first heat storage tank, and then enters the second evaporator to exchange heat with the high-temperature heat storage medium to become The working fluid then enters the superheater to absorb the heat of the high-temperature heat storage medium flowing out of the third heat storage tank, and then enters the first turbine to expand and perform work. The expanded medium-pressure water vapor enters the reheater to exchange heat with the heat storage medium from the fourth heat storage tank to increase its temperature, and then enters the second turbine to expand and perform work. Finally, the low-pressure steam enters the first condenser to exchange heat with the cold source, condenses into liquid and continues to circulate; the high-temperature heat storage medium flowing out of the first heat storage tank releases heat in the preheater and then enters the first cold storage tank for storage; the high-temperature heat storage medium flowing out of the third heat storage tank releases heat in the superheater, and then mixes with the heat storage medium flowing out of the second heat storage tank, enters the second evaporator to release heat, and then enters the second cold storage tank for storage together; the high-temperature heat storage medium flowing out of the fourth heat storage tank enters the reheater and then releases heat and is stored in the fourth cold storage tank.

[0031] A further improvement of the present invention is that when the system has waste heat input, the system closes the first control valve, the third control valve, the fourth control valve and the fifth control valve during the energy storage process, and opens the second control valve and the twenty-first control valve, so that the working fluid after throttling expansion enters the waste heat exchanger to absorb heat and evaporate into a saturated gas, and the working fluid after absorbing heat enters the second-stage compressor for pressure boosting; during the energy release process, the eleventh control valve, the twelfth control valve and the fourteenth control valve are closed, and the fifteenth control valve is opened, so that the working fluid after expansion and work in the first turbine enters the first condenser to exchange heat with the cold source and condense into a liquid.

[0032] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0033] In the water vapor energy storage system with cascade thermal storage provided by the present invention, the energy storage process and the energy release process are respectively completed by two closed loops, and there is no need to set up a separate storage tank to store the working medium, thereby reducing the system construction cost.

[0034] Furthermore, all devices in the present invention maintain a stable working state without alternating working conditions, thereby improving the overall operational stability of the system and reducing manufacturing costs.

[0035] Furthermore, the present invention unifies the working fluid in the energy storage circuit, energy release circuit, and cascade thermal storage circuit into water. Water is the most widely used working fluid in thermal systems, and the related technology is mature, safe, and reliable. This unified working fluid facilitates actual maintenance, repair, and subsequent upgrades.

[0036] Furthermore, the present invention adopts a stepped arrangement, which can realize stepped energy utilization, improve energy utilization rate, and adjust the pressure of each storage tank according to the stepped sequence, thereby reducing the number of high-pressure storage tanks.

[0037] Furthermore, the present invention uses a second condenser and a second evaporator in the cascade heat storage, which can utilize the large amount of latent heat released by the working medium water during the phase change process to improve the heat storage capacity of the system.

[0038] Furthermore, the present invention incorporates waste heat, which can be sourced from industrial or domestic waste heat. This technology has low waste heat temperature requirements and good adaptability to low-grade energy, facilitating system deployment. Introducing waste heat also eliminates some equipment, reducing system construction costs.

[0039] Furthermore, a plurality of control valves are arranged in the system of the present invention, which can flexibly adjust the operating conditions of the system and adjust the output power as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of a water vapor energy storage system with cascade thermal storage provided by an embodiment of the present invention.

[0041] Description of reference numerals:

[0042] 1. First evaporator; 2. First compressor; 3. Intercooler; 4. Second compressor; 5. Precooler; 6. Second condenser; 7. Aftercooler; 8. Waste heat exchanger; 9. Throttle valve; 10. Pump; 11. Preheater; 12. Second evaporator; 13. Superheater; 14. First turbine; 15. Reheater; 16. Second turbine; 17. First condenser; 18. First cold storage tank; 19. First heat storage tank; 20. Second cold storage tank; 21. Second heat storage tank; 22. Third cold storage tank; 23. Third heat storage tank; 24. Fourth cold storage tank; 25. Fourth heat storage tank; 26 , first control valve; 27, second control valve; 28, third control valve; 29, fourth control valve; 30, fifth control valve; 31, sixth control valve; 32, seventh control valve; 33, eighth control valve; 34, ninth control valve; 35, tenth control valve; 36, eleventh control valve; 37, twelfth control valve; 38, thirteenth control valve; 39, fourteenth control valve; 40, fifteenth control valve; 41, sixteenth control valve; 42, seventeenth control valve; 43, eighteenth control valve; 44, nineteenth control valve; 45, twentieth control valve; 46, twenty-first control valve. DETAILED DESCRIPTION

[0043] To make the purpose, technical effects, and technical solutions of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention. Based on the embodiments disclosed in the present invention, other embodiments obtained by ordinary technicians in this field without making any creative efforts should fall within the scope of protection of the present invention.

[0044] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0045] See also Figure 1 The embodiment of the present invention provides a water vapor energy storage system with cascade thermal storage, comprising: a first evaporator 1, a first compressor 2, an intercooler 3, a second compressor 4, a precooler 5, a second condenser 6, an aftercooler 7, a waste heat exchanger 8, a throttle valve 9, a pump 10, a preheater 11, a second evaporator 12, a superheater 13, a first turbine 14, a reheater 15, a second turbine 16, a first condenser 17, a first cold storage tank 18, a first heat storage tank 19, a second cold storage tank 20, a second heat storage tank 21, a third cold storage tank 22, a third heat storage tank 23, a fourth cold storage tank 24, and a fourth storage tank. The hot tank 25, and the first control valve 26, the second control valve 27, the third control valve 28, the fourth control valve 29, the fifth control valve 30, the sixth control valve 31, the seventh control valve 32, the eighth control valve 33, the ninth control valve 34, the tenth control valve 35, the eleventh control valve 36, the twelfth control valve 37, the thirteenth control valve 38, the fourteenth control valve 39, the fifteenth control valve 40, the sixteenth control valve 41, the seventeenth control valve 42, the eighteenth control valve 43, the nineteenth control valve 44, the twentieth control valve 45, and the twenty-first control valve 46, a total of twenty-one control valves.

[0046] The first outlet of the first evaporator 1 is connected to the inlet of the first compressor 2 through the first control valve 26. The outlet of the first compressor 2 is connected to the first inlet of the intercooler 3. The first outlet of the intercooler 3 is connected to the inlet of the second compressor 4 through the fifth control valve 30. The outlet of the second compressor 4 is connected to the first inlet of the precooler 5. The first outlet of the precooler 5 is connected to the first inlet of the second condenser 6. The first outlet of the second condenser 6 is connected to the first inlet of the aftercooler 7. The first outlet of the aftercooler 7 is divided into two paths after passing through the throttle valve 9. One path is connected to the first inlet of the first evaporator 1 through the third control valve 28, and the other path is connected to the inlet of the waste heat exchanger 8 through the second control valve 27. The outlet of the waste heat exchanger 8 merges with the first outlet of the intercooler 3 through the twenty-first control valve 46 and is connected to the inlet of the second compressor 4. This completes the energy storage cycle of the working medium.

[0047] The first outlet of the first condenser 17 is connected to the inlet of the pump 10 via the thirteenth control valve 38. The outlet of the pump 10 is connected to the first inlet of the preheater 11. The first outlet of the preheater 11 is connected to the first inlet of the second evaporator 12. The first outlet of the second evaporator 12 is connected to the first inlet of the superheater 13. The first outlet of the superheater 13 is connected to the inlet of the first turbine 14. The outlet of the first turbine 14 is divided into two routes. One route is connected to the first inlet of the reheater 15 via the fourteenth control valve 39. The first outlet of the reheater 15 is connected to the inlet of the second turbine 16. The outlet of the second turbine 16 is connected to the first inlet of the first condenser 17 via the twelfth control valve 37. The other route is connected to the first inlet of the first condenser 17 via the fifteenth control valve 40. This completes the energy release cycle of the working medium.

[0048] The first cold storage tank 18 is connected to the second inlet of the aftercooler 7 through the seventh control valve 32, the second outlet of the aftercooler 7 is connected to the inlet of the first heat storage tank 19, the outlet of the first heat storage tank 19 is connected to the second inlet of the preheater 11 through the twentieth control valve 45, and the second outlet of the preheater 11 is connected to the inlet of the first cold storage tank 18.

[0049] The second cold storage tank 20 is connected to the second inlet of the second condenser 6 via the eighth control valve 33. The second outlet of the second condenser 6 is split into two routes: one route is connected to the inlet of the second heat storage tank 21 via the ninth control valve 34. The outlet of the second heat storage tank 21 is connected to the second inlet of the second evaporator 12 via the nineteenth control valve 44. The second outlet of the second evaporator 12 is connected to the inlet of the second cold storage tank 20. The other route is connected to the second inlet of the precooler 5 via the sixth control valve 31. The second outlet of the precooler 5 is connected to the inlet of the third heat storage tank 23. The outlet of the third heat storage tank 23 is connected to the second inlet of the superheater 13 via the sixteenth control valve 41. The second outlet of the superheater 13 is split into two routes: one route is connected to the second inlet of the second evaporator 12 via the eighteenth control valve 43. The other route is connected to the inlet of the third cold storage tank 22 via the seventeenth control valve 42. The outlet of the third cold storage tank 22 is connected to the second inlet of the precooler 5 via the tenth control valve 35.

[0050] The outlet of the fourth cold storage tank 24 is connected to the second inlet of the intercooler 3 through the fourth control valve 29, the second outlet of the intercooler 3 is connected to the inlet of the fourth heat storage tank 25, the outlet of the fourth heat storage tank 25 is connected to the second inlet of the reheater 15 through the eleventh control valve 36, and the second outlet of the reheater 15 is connected to the inlet of the fourth cold storage tank 24.

[0051] The second inlet of the first evaporator 1 is a heat source, which provides heat for the evaporation of the working medium in the first evaporator 1 .

[0052] The second inlet of the first condenser 17 is a cold source, which provides cold energy for the condensation of the working medium in the first condenser 17. The above components constitute the entire energy storage and release part.

[0053] Preferably, when waste heat is present, waste heat exchanger 8 can be used to recover waste heat, increase the heat storage temperature of third heat storage tank 23, and thereby improve the work capacity of the working fluid at the inlet of first turbine 14. The inlet of waste heat exchanger 8 is connected to the outlet of throttle valve 9 via second control valve 27, and the outlet of waste heat exchanger 8 is connected to the inlet of second compressor 4 via a twenty-first control valve 46.

[0054] A control method for a water vapor energy storage system with cascade thermal storage according to an embodiment of the present invention specifically comprises the following steps:

[0055] In the initial state, all twenty-one control valves are closed and the system is in shutdown state;

[0056] When the user is in the off-peak period of electricity consumption, the second control valve 27, the tenth control valve 35, the eleventh control valve 36, the twelfth control valve 37, the thirteenth control valve 38, the fourteenth control valve 39, the fifteenth control valve 40, the sixteenth control valve 41, the seventeenth control valve 42, the eighteenth control valve 43, the nineteenth control valve 44, the twentieth control valve 45 and the twenty-first control valve 46 are closed, and the first control valve 26, the third control valve 28, the fourth control valve 29, the fifth control valve 30, the sixth control valve 31, the seventh control valve 32, the eighth control valve 33 and the ninth control valve 34 are opened, and the energy storage part of the cascade heat storage water vapor energy storage system starts working; the water vapor generated by the first evaporator 1 flows out from the first outlet of the first evaporator 1, passes through the first control valve 26 and enters the first compressor 2 for boosting, and then flows into the intercooler 3 to transfer heat to the low-temperature heat storage medium flowing out of the fourth cold storage tank 24, and then flows into the second compressor 4 to boost the pressure to a high temperature and high pressure state again, and the working medium flows into the precooler 5 to transfer heat to the second condenser The heat storage medium flowing out of the second outlet of 6 then enters the second condenser 6 and transfers heat to the heat storage medium flowing out of the second cold storage tank 20. The working medium releases a large amount of latent heat and condenses to a saturated water state. It then passes through the aftercooler 7 and transfers heat to the low-temperature heat storage medium flowing out of the first cold storage tank 18. The working medium is cooled to a supercooled water state and finally returns to the first evaporator 1 after throttling and expansion through the throttle valve 9. It exchanges heat with the heat source and evaporates into a gaseous state before continuing the cycle. The low-temperature heat storage medium at the outlet of the first cold storage tank 18 passes through the seventh control valve 32, absorbs heat in the aftercooler 7, and then enters the first heat storage tank 19 for storage. The heat storage medium in the second cold storage tank 20 passes through the eighth control valve 33, absorbs heat in the second condenser 6, and is then divided into two paths. One path passes through the ninth control valve 34 and enters the second heat storage tank 21 for storage. The other path passes through the sixth control valve 31 and enters the precooler 5 to absorb heat before entering the third heat storage tank 23 for storage. The low-temperature heat storage medium in the fourth cold storage tank 24 passes through the fourth control valve 29, absorbs heat in the intercooler 3, and then enters the fourth heat storage tank 25 for storage. At this point, the energy storage cycle of the working fluid is completed;

[0057] When the user is in the peak power consumption period, the first control valve 26, the second control valve 27, the third control valve 28, the fourth control valve 29, the fifth control valve 30, the sixth control valve 31, the seventh control valve 32, the eighth control valve 33, the ninth control valve 34, the tenth control valve 35, the fifteenth control valve 40, the seventeenth control valve 42 and the twenty-first control valve 46 are closed, and the eleventh control valve 36, the twelfth control valve 37, the thirteenth control valve 38, the fourteenth control valve 39, the sixteenth control valve 41, the eighteenth control valve 43, the nineteenth control valve 44 and the twentieth control valve 45 are opened, and the energy release part of the cascade heat storage water vapor energy storage system starts to work; low-temperature and low-pressure liquid water flows out of the first condenser 17, passes through the thirteenth control valve 38 and enters the pump 10, and after the working medium is pressurized, it enters the preheater 11 to absorb the heat of the high-temperature heat storage medium flowing out of the first heat storage tank 19, and then enters the second evaporator 12 and the high The hot heat storage medium is converted into saturated steam through heat exchange. The working medium then enters the superheater 13 to absorb the heat of the high-temperature heat storage medium flowing out of the third heat storage tank 23, and then enters the first turbine 14 to expand and perform work. The expanded medium-pressure water vapor enters the reheater 15 to exchange heat with the heat storage medium from the fourth heat storage tank 25 to increase its temperature, and then enters the second turbine 16 to expand and perform work. Finally, the low-pressure steam enters the first condenser 17 to exchange heat with the cold source, condenses into liquid and continues to circulate. The high-temperature heat storage medium flowing out of the first heat storage tank 19 releases heat in the preheater 11 and then enters the first cold storage tank 18 for storage. The high-temperature heat storage medium flowing out of the third heat storage tank 23 releases heat in the superheater 13, and then mixes with the heat storage medium flowing out of the second heat storage tank 21, enters the second evaporator 12 to release heat, and then enters the second cold storage tank 20 for storage. The high-temperature heat storage medium flowing out of the fourth heat storage tank 25 enters the reheater 15 to release heat and then is stored in the fourth cold storage tank 24. The energy release cycle of the working medium is now completed.

[0058] Preferably, when the system has waste heat input, during the energy storage process, the system can close the first control valve 26, the third control valve 28, the fourth control valve 29, and the fifth control valve 30, and open the second control valve 27 and the twenty-first control valve 46, allowing the working fluid after throttling expansion to enter the waste heat exchanger 8 to absorb heat and evaporate into a saturated gas state. The working fluid after absorbing heat can then directly enter the second-stage compressor for pressure boosting. During the energy release process, the eleventh control valve 36, the twelfth control valve 37, and the fourteenth control valve 39 can be closed, and the fifteenth control valve 40 can be opened, allowing the working fluid after expansion and work in the first turbine to directly enter the first condenser 17 for heat exchange with the cold source and condensation into a liquid state.

[0059] Optionally, the waste heat that can be utilized by the system includes medium and low temperature waste heat generated in domestic or industrial production processes.

[0060] Preferably, considering that the working fluid in this system can exist in subcooled, wet vapor, and superheated states, different types of heat storage media or with different thermodynamic parameters can be used to recover and utilize the heat of the working fluid in different states. In this case, the third cold storage tank 22 can be put into use. The specific operation method is as follows: During the energy storage process, the sixth control valve 31 is closed and the tenth control valve 35 is opened, allowing the heat storage medium flowing out of the third cold storage tank 22 to absorb the heat released by the working fluid in the precooler 5 and then enter the third heat storage tank 23 for storage. The heat storage medium in the second cold storage tank 20, after absorbing heat and increasing in temperature in the second condenser 6, directly enters the second heat storage tank 21 for storage. During the energy release process, the eighteenth control valve 43 is closed and the seventeenth control valve 42 is opened, allowing the high-temperature heat storage medium in the third heat storage tank 23 to flow out, release heat in the superheater 13, and enter the third cold storage tank 22 for storage. This operation establishes a new heat storage medium circuit and allows the type or thermodynamic parameters of the heat storage medium in the different storage tanks to be adjusted according to actual needs. This operation can further improve the system's energy storage capacity.

[0061] Preferably, when waste heat exists, it can be directly used to heat the working fluid at the first outlet of the aftercooler 7 and connected to the inlet of the second compressor 4 without starting the first compressor 2, thereby reducing system power consumption and improving system energy storage efficiency.

[0062] Preferably, the system adopts a stepped arrangement and is provided with multiple heat storage circuits, so the first cold storage tank 18 and the second cold storage tank 20 can use normal pressure tanks, reducing the number of high-pressure containers and lowering the device construction cost.

[0063] The control method of the present invention can achieve: storing energy by utilizing low-peak electricity during low-power consumption, and releasing energy during peak power consumption, thereby realizing cascaded energy utilization and having a higher energy utilization rate.

[0064] In summary, the present invention provides a water vapor energy storage system and control method with cascade thermal storage, which can realize energy storage and release according to the needs of the power grid and users, thereby reducing the user's electricity costs. Specific advantages include: (1) The energy storage process and energy release process of the present invention use separate closed circuits respectively, and there is no need to set up additional storage tanks to store the working fluid, thereby reducing construction costs; (2) The working fluid used in the energy storage circuit, energy release circuit and multiple cascade thermal storage circuits of the present invention is all water, which is convenient for the later maintenance, repair and upgrading of the system. It is the same working fluid used in traditional power stations, and the required equipment technology is mature, safe and reliable. (3) The present invention adopts a cascade arrangement of multiple storage tanks, which effectively reduces the pressure in some storage tanks and improves the safety and economy of the system; at the same time, the cascade arrangement can fully recover and utilize the heat carried by the working fluid in stages, greatly improving the energy utilization rate. (4) The present invention uses a second condenser and a second evaporator in the cascade thermal storage, which can utilize the large amount of latent heat released by the working fluid water during the phase change process to improve the heat storage capacity of the system. (5) The present invention can flexibly adjust its structure according to the actual application scenario, which can not only fully utilize the medium and low-grade waste heat, but also simplify the system structure and further improve the system economy. (6) The system is equipped with multiple control valves, which can achieve flexible and stable operation of the system, meet the needs of different loads, and make the system have good variable operating conditions.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art may still modify or make equivalent substitutions to the specific implementations of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A water vapor energy storage system with cascade thermal storage, characterized in that: It includes a first evaporator, a first compressor, an intercooler, a second compressor, a precooler, a second condenser, an aftercooler, a waste heat exchanger, a throttle valve, a pump, a preheater, a second evaporator, a superheater, a first turbine, a reheater, a second turbine, a first condenser, a first cold storage tank, a first heat storage tank, a second cold storage tank, a second heat storage tank, a third cold storage tank, a third heat storage tank, a fourth cold storage tank and a fourth heat storage tank; The first outlet of the first evaporator is connected to the inlet of the first compressor, the outlet of the first compressor is connected to the first inlet of the intercooler, the first outlet of the intercooler is connected to the inlet of the second compressor, the outlet of the second compressor is connected to the first inlet of the precooler, the first outlet of the precooler is connected to the first inlet of the second condenser, the first outlet of the second condenser is connected to the first inlet of the aftercooler, the first outlet of the aftercooler is divided into two paths after passing through the throttle valve, one path is connected to the first inlet of the first evaporator, and the other path is connected to the inlet of the waste heat exchanger, and the outlet of the waste heat exchanger merges with the first outlet of the intercooler and is connected to the inlet of the second compressor; The first outlet of the first condenser is connected to the pump inlet, the pump outlet is connected to the first inlet of the preheater, the first outlet of the preheater is connected to the first inlet of the second evaporator, the first outlet of the second evaporator is connected to the first inlet of the superheater, the first outlet of the superheater is connected to the inlet of the first turbine, the outlet of the first turbine is divided into two paths, one path is connected to the first inlet of the reheater, the first outlet of the reheater is connected to the inlet of the second turbine, the outlet of the second turbine is connected to the first inlet of the first condenser, and the other path is connected to the first inlet of the first condenser; The first cold storage tank is connected to the second inlet of the aftercooler, the second outlet of the aftercooler is connected to the inlet of the first heat storage tank, the outlet of the first heat storage tank is connected to the second inlet of the preheater, and the second outlet of the preheater is connected to the inlet of the first cold storage tank; The second cold storage tank is connected to the second inlet of the second condenser, and the second outlet of the second condenser is divided into two routes, one route is connected to the inlet of the second heat storage tank, the outlet of the second heat storage tank is connected to the second inlet of the second evaporator, the second outlet of the second evaporator is connected to the inlet of the second cold storage tank, and the other route is connected to the second inlet of the precooler, and the second outlet of the precooler is connected to the inlet of the third heat storage tank; the outlet of the third heat storage tank is connected to the second inlet of the superheater, and the second outlet of the superheater is divided into two routes, one route is connected to the second inlet of the second evaporator, and the other route is connected to the inlet of the third cold storage tank, and the outlet of the third cold storage tank is connected to the second inlet of the precooler; The fourth cold storage tank outlet is connected to the second inlet of the intercooler, the second outlet of the intercooler is connected to the inlet of the fourth heat storage tank, the fourth heat storage tank outlet is connected to the second inlet of the reheater, and the second outlet of the reheater is connected to the inlet of the fourth cold storage tank; The second inlet of the first evaporator is a heat source, which provides heat for the evaporation of the working medium in the first evaporator; The second inlet of the first condenser is a cold source, which provides cold energy for the condensation of the working medium in the first condenser.

2. The water vapor energy storage system with cascade thermal storage according to claim 1, characterized in that: Also includes a first control valve, a second control valve, a third control valve, a fourth control valve, a fifth control valve, a sixth control valve, a seventh control valve, an eighth control valve, a ninth control valve, a tenth control valve, an eleventh control valve, a twelfth control valve, a thirteenth control valve, a fourteenth control valve, a fifteenth control valve, a sixteenth control valve, a seventeenth control valve, an eighteenth control valve, a nineteenth control valve, a twentieth control valve, and a twenty-first control valve; The first outlet of the first evaporator is connected to the inlet of the first compressor through the first control valve, the first outlet of the intercooler is connected to the inlet of the second compressor through the fifth control valve, the first outlet of the aftercooler is divided into two paths after passing through the throttle valve, one path is connected to the first inlet of the first evaporator through the third control valve, and the other path is connected to the inlet of the waste heat exchanger through the second control valve. The outlet of the waste heat exchanger is connected to the first outlet of the intercooler through the twenty-first control valve and connected to the inlet of the second compressor; The first outlet of the first condenser is connected to the pump inlet via the thirteenth control valve; the first turbine outlet is split into two routes: one route is connected to the first inlet of the reheater via the fourteenth control valve, the first outlet of the reheater is connected to the second turbine inlet, the second turbine outlet is connected to the first inlet of the first condenser via the twelfth control valve, and the other route is connected to the first inlet of the first condenser via the fifteenth control valve. The first cold storage tank is connected to the second inlet of the aftercooler through the seventh control valve, and the outlet of the first heat storage tank is connected to the second inlet of the preheater through the 20th control valve; The second cold storage tank is connected to the second inlet of the second condenser through the eighth control valve. The second outlet of the second condenser is divided into two routes, one of which is connected to the inlet of the second heat storage tank through the ninth control valve. The outlet of the second heat storage tank is connected to the second inlet of the second evaporator through the nineteenth control valve, and the other route is connected to the second inlet of the precooler through the sixth control valve. The second outlet of the precooler is connected to the inlet of the third heat storage tank; the outlet of the third heat storage tank is connected to the second inlet of the superheater through the sixteenth control valve. The second outlet of the superheater is divided into two routes, one of which is connected to the second inlet of the second evaporator through the eighteenth control valve, and the other route is connected to the inlet of the third cold storage tank through the seventeenth control valve. The outlet of the third cold storage tank passes through the tenth control valve and the sixth control valve and then merges to connect to the second inlet of the precooler; The outlet of the fourth cold storage tank is connected to the second inlet of the intercooler through the fourth control valve, and the outlet of the fourth heat storage tank is connected to the second inlet of the reheater through the eleventh control valve.

3. The water vapor energy storage system with cascade thermal storage according to claim 2, characterized in that: The energy storage process and energy release process of this system are independent closed loops.

4. The water vapor energy storage system with cascade thermal storage according to claim 2, characterized in that: The working fluid used in the energy storage circuit, energy release circuit and multiple cascade heat storage circuits is water; The energy storage circuit consists of the first evaporator, the first compressor, the intercooler, the second compressor, the precooler, the second condenser, the aftercooler, the throttle valve, the waste heat heater, the first control valve, the second control valve, the third control valve, the fifth control valve, the sixth control valve and the twenty-first control valve; the energy release circuit consists of the first condenser, the pump, the preheater, the second evaporator, the superheater, the first turbine, the reheater, the second turbine, the twelfth control valve, the thirteenth control valve, the fourteenth control valve, the fifteenth control valve and the eighteenth control valve; the cascade heat storage circuit consists of the first cold storage tank, the first heat storage tank, the second cold storage tank, the second heat storage tank, the third cold storage tank, the third heat storage tank, the fourth cold storage tank, the fourth heat storage tank, the fourth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve, the eleventh control valve, the sixteenth control valve, the seventeenth control valve, the nineteenth control valve and the twentieth control valve.

5. The water vapor energy storage system with cascade thermal storage according to claim 2, characterized in that: The system adopts a cascade arrangement of multiple storage tanks to achieve cascade energy utilization and improve energy utilization rate.

6. The water vapor energy storage system with cascade thermal storage according to claim 2, characterized in that: The second condenser and the second evaporator are used in the cascade heat storage, which utilizes the large amount of latent heat released by the working medium water during the phase change process to improve the heat storage capacity of the system.

7. The water vapor energy storage system with cascade thermal storage according to claim 2, characterized in that: When waste heat exists, the waste heat exchanger is put into use to recover the waste heat and increase the heat storage temperature of the third heat storage tank, thereby improving the working capacity of the working medium at the first turbine inlet.

8. The water vapor energy storage system with cascade thermal storage according to claim 2, characterized in that: When the system is used in places with stable waste heat supply, the first-stage compressor, the first evaporator, the intercooler, the fourth cold storage tank, the fourth heat storage tank, the reheater and the second turbine are eliminated.

9. The control method of the water vapor energy storage system with cascade thermal storage according to claim 2, characterized in that: include: In the initial state, all twenty-one control valves are closed and the system is in shutdown state; When the user is in the off-peak period of electricity consumption, the second control valve, the tenth control valve, the eleventh control valve, the twelfth control valve, the thirteenth control valve, the fourteenth control valve, the fifteenth control valve, the sixteenth control valve, the seventeenth control valve, the eighteenth control valve, the nineteenth control valve, the twentieth control valve and the twenty-first control valve are closed, and the first control valve, the third control valve, the fourth control valve, the fifth control valve, the sixth control valve, the seventh control valve, the eighth control valve and the ninth control valve are opened, and the energy storage part of the cascade heat storage water vapor energy storage system works; the water vapor generated by the first evaporator flows out from the first outlet of the first evaporator, passes through the first control valve and enters the first compressor for pressure boosting, and then flows into the intercooler to transfer heat to the low-temperature heat storage medium flowing out of the fourth cold storage tank, and then flows into the second compressor to boost the pressure to a high temperature and high pressure state again, and the working medium flows into the precooler to transfer heat to the low-temperature heat storage medium flowing out of the second outlet of the second condenser The heat storage medium then enters the second condenser to transfer heat to the heat storage medium flowing out of the second cold storage tank. The working medium releases a large amount of latent heat and condenses to a saturated water state. It then passes through the aftercooler to transfer heat to the low-temperature heat storage medium flowing out of the first cold storage tank. The working medium is cooled to a supercooled water state and finally returns to the first evaporator after throttling and expansion by the throttle valve. It exchanges heat with the heat source and evaporates into a gaseous state and continues to circulate; the low-temperature heat storage medium at the outlet of the first cold storage tank passes through the seventh control valve and absorbs heat in the aftercooler before entering the first heat storage tank for storage; the heat storage medium in the second cold storage tank passes through the eighth control valve and absorbs heat in the second condenser, and then is divided into two paths, one path passes through the ninth control valve and enters the second heat storage tank for storage, and the other path passes through the sixth control valve and enters the precooler to absorb heat, and then enters the third heat storage tank for storage; the low-temperature heat storage medium in the fourth cold storage tank passes through the fourth control valve and absorbs heat in the intercooler, and then enters the fourth heat storage tank for storage; When the user is at the peak of electricity consumption, the first control valve, the second control valve, the third control valve, the fourth control valve, the fifth control valve, the sixth control valve, the seventh control valve, the eighth control valve, the ninth control valve, the tenth control valve, the fifteenth control valve, the seventeenth control valve and the twenty-first control valve are closed, and the eleventh control valve, the twelfth control valve, the thirteenth control valve, the fourteenth control valve, the sixteenth control valve, the eighteenth control valve, the nineteenth control valve and the twenty-first control valve are opened, and the energy release part of the cascade heat storage water vapor energy storage system starts to work; low-temperature and low-pressure liquid water flows out of the first condenser, passes through the thirteenth control valve and enters the pump, and after the working fluid is pressurized, it enters the preheater to absorb the heat of the high-temperature heat storage medium flowing out of the first heat storage tank, and then enters the second evaporator to exchange heat with the high-temperature heat storage medium to become The working fluid then enters the superheater to absorb the heat of the high-temperature heat storage medium flowing out of the third heat storage tank, and then enters the first turbine to expand and perform work. The expanded medium-pressure water vapor enters the reheater to exchange heat with the heat storage medium from the fourth heat storage tank to increase its temperature, and then enters the second turbine to expand and perform work. Finally, the low-pressure steam enters the first condenser to exchange heat with the cold source, condenses into liquid and continues to circulate; the high-temperature heat storage medium flowing out of the first heat storage tank releases heat in the preheater and then enters the first cold storage tank for storage; the high-temperature heat storage medium flowing out of the third heat storage tank releases heat in the superheater, and then mixes with the heat storage medium flowing out of the second heat storage tank, enters the second evaporator to release heat, and then enters the second cold storage tank for storage together; the high-temperature heat storage medium flowing out of the fourth heat storage tank enters the reheater and then releases heat and is stored in the fourth cold storage tank.

10. The control method of a water vapor energy storage system with cascade thermal storage according to claim 9, characterized in that: When the system has waste heat input, the system closes the first control valve, the third control valve, the fourth control valve and the fifth control valve in the energy storage process, and opens the second control valve and the twenty-first control valve, so that the working fluid after throttling expansion enters the waste heat exchanger to absorb heat and evaporate into a saturated gas, and the working fluid after absorbing heat enters the second-stage compressor for pressure boosting; during the energy release process, the eleventh control valve, the twelfth control valve and the fourteenth control valve are closed, and the fifteenth control valve is opened, so that the working fluid after expansion and work in the first turbine enters the first condenser to exchange heat with the cold source and condense into a liquid.

Images