Heat pump and heat storage coupled system for exhaust steam waste heat recovery of coal-fired power plant

Abstract

The application discloses a heat pump and heat storage coupling system for recovering exhaust steam waste heat of a coal-fired power plant, which comprises an air-cooled unit thermal system and a heat pump system; the air-cooled unit thermal system comprises a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator, a high-pressure heater, a feed water pump, a deaerator, a low-pressure heater, a condensate pump and a condenser; and the heat pump system comprises a filter, a regenerator, a compressor, a condenser, an expander, a heat storage tank, a heat exchanger, a cold storage tank and a motor. The heat pump system is used for consuming the surplus power of the coal-fired power plant in the low power consumption period, and improving the deep peak regulation capacity of the coal-fired power plant; the heat storage tank and the cold storage tank are additionally arranged to store and transfer heat, thereby improving the energy utilization rate; the condenser of the air-cooled unit is used to replace the evaporator of the heat pump system, thereby saving the modification cost of the heat pump system, and improving the performance coefficient of the heat pump system compared with the normal temperature air used as the heat source of the evaporator of the heat pump system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy, in particular to a heat pump and heat storage coupling system for recovering exhaust steam waste heat of a coal-fired power plant. BACKGROUND

[0002] With the continuous growth of global energy demand and the improvement of environmental protection awareness, improving energy utilization efficiency and reducing energy waste have become urgent problems to be solved in the power industry. In traditional coal-fired power plants, a large amount of waste heat is generated during power generation, especially in air-cooled units, exhaust steam waste heat is usually cooled by air and then directly discharged into the atmosphere. This practice not only causes a lot of energy waste, but also increases environmental heat pollution.

[0003] How to effectively recover the waste heat of a coal-fired power plant, improve energy utilization efficiency and reduce environmental pollution is a technical problem to be solved in the prior art. SUMMARY

[0004] The present application proposes a heat pump and heat storage coupling system for recovering exhaust steam waste heat of a coal-fired power plant to solve at least one of the technical problems in the background art. The system comprises:

[0005] An air-cooled unit thermal system and a heat pump system; the air-cooled unit thermal system comprises a boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator, a high-pressure heater, a feed water pump, a deaerator, a low-pressure heater, a condensate pump and a condenser; the heat pump system comprises a filter, a regenerator, a compressor, a condenser, an expander, a heat storage tank, a heat exchanger, a cold storage tank and a motor;

[0006] In the air-cooled unit thermal system, the boiler, the high-pressure cylinder, the medium-pressure cylinder, the low-pressure cylinder, the condenser, the condensate pump, the low-pressure heater, the deaerator, the feed water pump and the high-pressure heater are connected in series to form a loop, the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder are connected in series, the extraction port of the high-pressure cylinder and the medium-pressure cylinder is connected to the high-pressure heater, and the extraction port of the medium-pressure cylinder and the low-pressure cylinder is connected to the low-pressure heater;

[0007] In the heat pump system, the filter, the regenerator, the compressor, the condenser and the expander are connected in series, the condenser, the heat storage tank, the heat exchanger and the cold storage tank are connected in series to form a loop, one end of the compressor is connected to the motor, and the other end is connected to the expander.

[0008] Optionally, the boiler is used to send steam into the high-pressure cylinder to do work; the high-pressure cylinder is used to reduce the pressure and temperature of the steam to the level required by the intermediate-pressure cylinder and send the steam into the intermediate-pressure cylinder to do work; the intermediate-pressure cylinder is used to reduce the pressure and temperature of the steam to the level required by the low-pressure cylinder and send the steam into the low-pressure cylinder to do work; the low-pressure cylinder is used to drive the generator to generate electricity; the high-pressure heater uses steam extracted from the high-pressure and intermediate-pressure cylinders to heat the feedwater; the deaerator is used to remove oxygen from the feedwater to ensure feedwater quality; the feedwater pump is used to increase the feedwater pressure to meet the boiler feedwater requirements; the low-pressure heater uses steam extracted from the intermediate-pressure and low-pressure cylinders to heat the condensate; the condenser is used to condense the steam from the low-pressure cylinder into water and to establish and maintain a vacuum at the low-pressure cylinder exhaust point; the condensate pump is used to pressurize the condensate at the condenser outlet and send it to the regenerative cycle.

[0009] Optionally, the condenser is used to exchange heat between the two streams of hot and cold working fluid from the heat exchanger outlet and the compressor outlet; the regenerator is used to exchange heat between the two streams of hot and cold working fluid from the filter outlet and the condenser outlet; the heat storage tank is used to store the hot molten salt after heat exchange in the condenser, and to output heat when there is a heat demand; the cold storage tank is used to store the cold molten salt after heat exchange; the heat exchanger is used to exchange heat between the working fluid from the heat storage tank outlet and the condensate, and the working fluid after heat exchange returns to the air-cooled unit's thermal system, forming a closed loop; the expander is used to recover the waste heat of the circulating working fluid at the regenerator outlet.

[0010] Optionally, the heat pump system is an air-type heat pump, which uses a portion of the low-temperature hot air from the condenser outlet as the circulating working fluid of the heat pump system.

[0011] Optionally, the air at the condenser outlet is filtered by a filter and then enters the regenerator. After exchanging heat with the circulating working fluid at the condenser outlet, it enters the compressor for pressurization. Then, it enters the condenser and exchanges heat with the condensate at the heat exchanger outlet before flowing into the regenerator for secondary heat exchange. Finally, it enters the expansion unit to form a cycle. After being expanded by the expansion unit, the air becomes superheated steam and is discharged into the atmosphere.

[0012] Optionally, the electrical energy required by the motor can be generated by a generator.

[0013] Optionally, the heat storage medium is molten salt. During heat storage, the cold molten salt in the cold storage tank is heated by a heat pump system to become hot molten salt, which is then stored in the heat storage tank. When releasing heat, the heat pump system stops operating, and the hot molten salt in the heat storage tank returns to the cold storage tank after exchanging heat through a heat exchanger, forming a closed loop and realizing the recycling of molten salt.

[0014] Optionally, the cold flow entering the heat exchanger originates from the condensate between the feedwater pump outlet and the high-pressure heater inlet.

[0015] Optionally, the air entering the regenerator is filtered through a filter to remove dust, fine particulate matter, impurities, or contaminants from the air, preventing blockage or corrosion of the regenerator, thereby improving the efficiency and lifespan of the equipment and ensuring the normal operation of the heat pump system.

[0016] Optionally, the extraction port of the intermediate pressure cylinder is connected to the deaerator.

[0017] The beneficial effects of this invention are as follows:

[0018] This invention proposes a heat pump and thermal storage coupling system for recovering waste heat from exhaust steam in coal-fired power plants. The heat pump system utilizes surplus electricity generated during off-peak hours, improving the plant's deep peak-shaving capacity. By adding thermal and cold storage tanks, heat is stored and transferred, increasing energy utilization. The condenser of an air-cooled unit replaces the evaporator in the heat pump system, saving on system retrofit costs. Compared to using ambient air as the heat source for the evaporator, utilizing waste heat from hot air improves the system's Coefficient of Performance (COP). Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0020] Figure 1 This is a schematic diagram of a heat pump and thermal storage coupling system for recovering waste heat from exhaust steam in a coal-fired power plant, according to an embodiment of the present invention.

[0021] In the diagram: 1-Air-cooled unit thermal system, 2-Heat pump system, 3-Boiler, 4-High-pressure cylinder, 5-Medium-pressure cylinder, 6-Low-pressure cylinder, 7-Generator, 8-High-pressure heater, 9-Feed water pump, 10-Deaerator, 11-Low-pressure heater, 12-Condensate pump, 13-Condenser, 14-Filter, 15-Regenerator, 16-Compressor, 17-Condenser, 18-Expander, 19-Heat storage tank, 20-Heat exchanger, 21-Cold storage tank, 22-Electric motor. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion, for example, including a series of products or devices that are not necessarily limited to those explicitly listed, but may include other units not explicitly listed or inherent to these products or devices.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] Figure 1 This is a schematic diagram of a heat pump and thermal storage coupling system for waste heat recovery from exhaust steam in a coal-fired power plant, as described in an embodiment of the present invention. Figure 1 As shown, in one embodiment of the present invention, the heat pump and heat storage coupling system for waste heat recovery from exhaust steam of the coal-fired power plant of the present invention includes: an air-cooled unit thermal system 1 and a heat pump system 2.

[0026] like Figure 1 As shown, the air-cooled unit's thermal system 1 includes: a boiler 3, a high-pressure cylinder 4, a medium-pressure cylinder 5, a low-pressure cylinder 6, a generator 7, a high-pressure heater 8, a feedwater pump 9, a deaerator 10, a low-pressure heater 11, a condensate pump 12, and a condenser 13.

[0027] like Figure 1 As shown, the heat pump system 2 includes: a filter 14, a regenerator 15, a compressor 16, a condenser 17, an expander 18, a heat storage tank 19, a heat exchanger 20, a cold storage tank 21, and an electric motor 22.

[0028] like Figure 1 As shown, in the air-cooled unit's thermal system 1, the boiler 3, high-pressure cylinder 4, intermediate-pressure cylinder 5, low-pressure cylinder 6, condenser 13, condensate pump 12, low-pressure heater 11, deaerator 10, feedwater pump 9, and high-pressure heater 8 are connected in series to form a loop. The high-pressure cylinder 4, intermediate-pressure cylinder 5, low-pressure cylinder 6, and generator 7 are connected in series. The extraction ports of high-pressure cylinder 4 and intermediate-pressure cylinder 5 are connected to the high-pressure heater 8, and the extraction ports of intermediate-pressure cylinder 5 and low-pressure cylinder 6 are connected to the low-pressure heater 11.

[0029] like Figure 1As shown, in heat pump system 2, filter 14, regenerator 15, compressor 16, condenser 17, and expander 18 are connected in sequence. Condenser 17, heat storage tank 19, heat exchanger 20, and cold storage tank 21 are connected in series to form a loop. One end of compressor 16 is connected to motor 22, and the other end is connected to expander 18.

[0030] In one embodiment of the invention, boiler 3 is used to feed steam into high-pressure cylinder 4 to perform work. High-pressure cylinder 4 is used to reduce the pressure and temperature of the steam to the level required by intermediate-pressure cylinder 5 and feed the steam into intermediate-pressure cylinder 5 to perform work. Intermediate-pressure cylinder 5 is used to reduce the pressure and temperature of the steam to the level required by low-pressure cylinder 6 and feed the steam into low-pressure cylinder 6 to perform work. Low-pressure cylinder 6 is used to drive generator 7 to generate electricity. High-pressure heater 8 uses steam drawn from high-pressure cylinder 4 and intermediate-pressure cylinder 5 to heat feedwater. Deaerator 10 is used to remove oxygen from feedwater to ensure feedwater quality. Feedwater pump 9 is used to increase feedwater pressure to meet boiler feedwater requirements. Low-pressure heater 11 uses steam drawn from intermediate-pressure cylinder 5 and low-pressure cylinder 6 to heat condensate. Condenser 13 is used to condense steam from low-pressure cylinder 6 into water and to establish and maintain a vacuum at the exhaust of low-pressure cylinder 6. Condensate pump 12 is used to pressurize the condensate at the outlet of condenser 13 and send it to the regenerative cycle.

[0031] In one embodiment of the present invention, condenser 17 is used to exchange heat between two streams of hot and cold working fluid from the outlet of heat exchanger 20 and the outlet of compressor 16. Regenerator 15 is used to exchange heat between two streams of hot and cold working fluid from the outlet of filter 14 and the outlet of condenser 17. Heat storage tank 19 is used to store the hot molten salt after heat exchange in condenser 17, and to output heat when there is a heat demand. Cold storage tank 21 is used to store the cold molten salt after heat exchange. Heat exchanger 20 is used to exchange heat between the working fluid from the outlet of heat storage tank 19 and condensate, and the working fluid after heat exchange returns to the air-cooled unit thermal system 1, forming a closed loop. Expander 18 is used to recover the waste heat of the circulating working fluid at the outlet of regenerator 15.

[0032] Therefore, the heat pump and thermal storage coupling system for recovering waste heat from exhaust steam in a coal-fired power plant of the present invention has the following characteristics:

[0033] 1. The system of this invention replaces the evaporator of the heat pump system with the condenser of the air-cooled unit thermal system, which can effectively recover and utilize the waste heat emitted by the power plant, improve the energy utilization rate, and achieve the purpose of energy conservation and emission reduction. Compared with the traditional heat pump system, it simplifies the system structure and saves construction costs.

[0034] 2. The system of the present invention uses a heat exchanger to transfer the waste heat of exhaust steam in the low-temperature circulating cooling water to the boiler feedwater. By heating the boiler feedwater, fuel consumption is reduced and the circulating thermal efficiency of the air-cooled unit's thermal system is improved.

[0035] In one embodiment of the present invention, one end of the compressor 16 is connected to the motor 22, and the other end is coaxially connected to the expander 18.

[0036] In one embodiment of the present invention, the steam extraction ports of the high-pressure cylinder 4, the intermediate-pressure cylinder 5, and the low-pressure cylinder 6 are respectively connected to the high-pressure heater 8, the deaerator 10, and the low-pressure heater 11.

[0037] In one embodiment of the present invention, the heat pump system 2 is an air-type heat pump that uses a portion of the low-temperature hot air from the outlet of the condenser 13 as the circulating working fluid of the heat pump system 2.

[0038] This invention effectively recovers and utilizes the low-temperature waste heat that might otherwise be emitted by introducing the low-temperature hot air from the condenser 13 outlet into the heat pump system 2. This not only reduces heat loss from air emissions but also converts low-temperature waste heat into usable thermal energy, thereby improving overall energy efficiency. The heat pump system of this invention uses air as the circulating working fluid, which is readily available and inexpensive compared to traditional working fluids. Simultaneously, the fluidity and thermodynamic properties of air are fully utilized in this system, allowing the heat pump system to maintain good operating performance under various conditions. This invention extracts low-temperature air from the condenser 13 into the heat pump system, where the working fluid undergoes compression, condensation, expansion, and heat exchange processes, forming a closed-loop cycle. This design reduces heat loss and stores and regulates heat through the heat storage tank 19 and the cold storage tank 21, ensuring sufficient heat supply at different times. By using low-temperature hot air as the circulating working fluid, this air-based heat pump solution further improves the system's heat recovery efficiency, achieving a more energy-efficient and environmentally friendly operation.

[0039] In one embodiment of the present invention, the air at the outlet of condenser 13 is filtered by filter 14 and enters regenerator 15. After exchanging heat with the circulating working fluid at the outlet of condenser 17, it enters compressor 16 for pressurization. Then it enters condenser 17 and exchanges heat with condensate at the outlet of heat exchanger 20. After flowing into regenerator 15 for secondary heat exchange, it enters expander 18 to form a cycle. After being expanded by expander 18, the air becomes superheated steam and is discharged into the atmosphere.

[0040] In this invention, the low-temperature hot air from the condenser 13 outlet first passes through the filter 14 to remove impurities, ensuring the cleanliness of the air entering the heat pump system. The filtered air then enters the regenerator 15, where it undergoes its first heat exchange with the circulating working fluid from the condenser 17 outlet. This process preheats the air by using the high-temperature circulating working fluid from the condenser 17, raising its temperature and making it more suitable for subsequent compression processing.

[0041] After initial heat exchange, the air flows into compressor 16, where it is further compressed, significantly increasing its temperature and pressure. This compression significantly improves the air's thermodynamic properties, giving it greater potential thermal energy.

[0042] The pressurized, high-temperature, high-pressure air enters the condenser 17 and exchanges heat with the condensate water exiting the heat exchanger 20. At this time, the condensate water is at a lower temperature and can effectively absorb heat from the air, while the air is further cooled. This process in the condenser 17 transfers the heat from the air to the condensate water, making it a heat source that can be used in other system processes.

[0043] The air exiting the condenser 17 flows back into the regenerator 15, where it undergoes secondary heat exchange with the working fluid (such as molten salt in the heat storage tank). This process not only further recovers residual heat from the air but also increases the overall thermal efficiency of the system through repeated heat exchange, making full use of the energy in every part.

[0044] After secondary heat exchange in the regenerator, the air flows into the expander 18. In the expander, the air pressure rapidly decreases, causing expansion and releasing its mechanical energy and some thermal energy. Simultaneously, the temperature drops sharply, becoming superheated steam. The expanded superheated steam is eventually discharged into the atmosphere, completing a full cycle.

[0045] This invention utilizes waste heat by subjecting the air to two heat exchanges (a regenerator and a condenser), storing the heat in condensate or molten salt to maximize waste heat recovery. During the circulation process within multiple heat exchangers, heat is exchanged and utilized multiple times, reducing system energy loss and enhancing the overall system's heat recovery efficiency. The expander design ensures that the air becomes superheated steam upon final discharge into the atmosphere, further releasing heat while reducing the cooling burden on the environment. The combination of air pressurization, heat exchange, and expansion processes enables efficient operation of the heat pump system, while also reducing the cooling load and energy consumption of the entire power plant system. This air-based heat pump system design achieves efficient heat management through a refined heat exchange and compression process, maximizing waste heat utilization and further improving the overall system efficiency and environmental performance.

[0046] In one embodiment of the present invention, the electrical energy required by the motor 22 is generated by the generator 7, thereby improving the deep peak-shaving capacity of the coal-fired power plant during off-peak hours.

[0047] During periods of low electricity demand, power plants typically face a decline in power generation load. This invention utilizes the excess electricity generated by generator 7 during these off-peak periods to drive the motor 22 in the heat pump system, effectively absorbing this excess energy and reducing the impact of frequent start-ups and shutdowns on equipment lifespan and efficiency. This design not only maintains the operating efficiency of the generator set but also stabilizes the grid load and enhances the peak-shaving capacity of coal-fired power plants. By using the electricity generated by generator 7 to drive the motor 22 of the heat pump system during off-peak periods, this invention effectively utilizes excess electricity generated during power generation, reducing energy waste. Furthermore, the heat pump system can recover and store waste heat (e.g., through a heat storage tank 19), releasing the stored heat when electricity demand increases for heating or power generation, improving system flexibility and responsiveness.

[0048] In one embodiment of the present invention, a heat storage tank 19 and a cold storage tank 21 are added to the system. The heat storage medium is molten salt. During heat storage, the cold molten salt in the cold storage tank 21 is heated by the heat pump system 2 to become hot molten salt, which is then stored in the heat storage tank 19. When releasing heat, the heat pump system 2 stops operating, and the hot molten salt in the heat storage tank 19 returns to the cold storage tank 21 after exchanging heat through the heat exchanger 20, forming a closed loop and realizing the recycling of molten salt.

[0049] Molten salt, as a heat storage medium, possesses excellent thermophysical properties, enabling it to store large amounts of heat while maintaining high thermal stability. Molten salt does not undergo significant physical or chemical changes at high temperatures, making it suitable as a long-term heat storage medium. During heat storage, molten salt can store heat at high temperatures, while during heat release, it can effectively transfer heat to the working fluid or other system equipment through heat exchangers, ensuring full utilization of thermal energy.

[0050] This invention utilizes a closed-loop circulation of molten salt between the thermal storage tank 19 and the cold storage tank 21, enabling the system to repeatedly perform heat storage and release operations without frequent replacement or addition of new media. This design greatly simplifies operation and management and reduces energy and material waste. This invention effectively recovers and stores waste heat, releasing it when needed, thus avoiding waste. By utilizing the high heat storage capacity of molten salt and the efficient operation of the heat pump, the overall energy efficiency of the system is significantly improved. The recycling of molten salt not only reduces heat emissions to the outside world but also reduces dependence on traditional coal combustion through waste heat recovery and reuse, thereby reducing greenhouse gas and other pollutant emissions and contributing to environmental protection.

[0051] The addition of the thermal storage tank 19 and the cold storage tank 21 in this invention enables the efficient use of molten salt as a thermal storage medium, forming a closed-loop system. This solution significantly improves the heat storage and management capabilities, ensuring the flexible operation of the heat pump system under different operating conditions. Through the recycling of molten salt, the system achieves efficient waste heat recovery and energy storage, enhances the peak-shaving capacity of coal-fired power plants, reduces energy waste, and lowers environmental impact.

[0052] In one embodiment of the present invention, the cold flow entering the heat exchanger 20 originates from the condensate after the outlet of the feed water pump 9 and before the inlet of the high-pressure heater 8.

[0053] This invention utilizes the condensate between the outlet of the feedwater pump 9 and the inlet of the high-pressure heater 8 as a cold flow. This cold flow has a relatively low temperature when it enters the heat exchanger 20, effectively absorbing the heat from the high-temperature air returning from the heat pump system. The heat exchanger 20 transfers some of the heat to this cold condensate by exchanging heat with the working fluid of the heat pump system. The condensate, after its temperature rises, enters the high-pressure heater 8 for further heating of the feedwater. This process not only fully recovers the heat from the heat pump system but also preheats the condensate before it enters the high-pressure heater 8, reducing the load on the high-pressure heater 8.

[0054] This invention introduces the condensate between the outlet of the feedwater pump 9 and the inlet of the high-pressure heater 8 as a cold flow into the heat exchanger 20, effectively utilizing the cold energy of the condensate and improving the waste heat recovery efficiency of the heat pump system. Simultaneously, this design reduces the load on the high-pressure heater, optimizes the thermodynamic cycle of the entire power generation system, and significantly improves energy utilization efficiency and overall system stability.

[0055] In one embodiment of the present invention, the air entering the regenerator 15 is filtered by a filter 14 to remove dust, fine particulate matter, impurities or contaminants from the air, so as to avoid clogging or corrosion of the regenerator 15, thereby improving the efficiency and life of the equipment and ensuring the normal operation of the heat pump system 2.

[0056] If impurities, dust, and fine particulate matter in the air enter the regenerator without filtration, they may adhere to the heat exchange surfaces, causing blockage and affecting heat exchange efficiency. Furthermore, certain chemicals or impurities may react with the equipment materials, causing corrosion and further reducing the equipment's lifespan. This invention, through filter 14, effectively removes these airborne contaminants, preventing blockage and corrosion of the regenerator, thereby improving its operating efficiency and durability.

[0057] Furthermore, when the regenerator surface is clean and free of contaminants, the heat exchange efficiency between the air and the working fluid is higher. If impurities adhere to the heat exchange surface, it may lead to a decrease in the heat transfer performance of the heat exchanger, reducing the energy recovery effect of the system. The use of filter 14 ensures that the air entering the regenerator is clean, thereby guaranteeing the heat transfer efficiency of the heat exchanger and improving the overall performance of the heat pump system 2.

[0058] In one embodiment of the present invention, the extraction port of the intermediate pressure cylinder 5 is connected to the deaerator 10.

[0059] As can be seen from the above embodiments, this invention proposes a heat pump and thermal storage coupling system for recovering waste heat from exhaust steam in coal-fired power plants. Through the heat pump system, surplus electricity from coal-fired power plants during off-peak hours is consumed, improving the deep peak-shaving capacity of the power plants. By adding thermal and cold storage tanks to store and transfer heat, energy utilization efficiency is improved. Using the condenser of an air-cooled unit instead of the evaporator in the heat pump system saves on the cost of system modification. Compared to using ambient air as the heat source for the evaporator, utilizing the waste heat of hot air improves the COP of the heat pump system. Simultaneously, the stored heat can heat feedwater, reheat cold-section steam, or generate main steam, reducing turbine extraction and increasing unit output. This invention can broaden the load operating range of coal-fired power generation systems and improve system operational flexibility, showing promising application prospects in the field of thermal power generation.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A heat pump and thermal storage coupling system for recovering waste heat from exhaust steam in a coal-fired power plant, characterized in that, include: The air-cooled unit has a thermal system (1) and a heat pump system (2). The air-cooled unit thermal system (1) includes: a boiler (3), a high-pressure cylinder (4), a medium-pressure cylinder (5), a low-pressure cylinder (6), a generator (7), a high-pressure heater (8), a feed water pump (9), a deaerator (10), a low-pressure heater (11), a condensate pump (12), and a condenser (13). The heat pump system (2) includes: a filter (14), a regenerator (15), a compressor (16), a condenser (17), an expander (18), a thermal storage tank (19), a heat exchanger (20), a cold storage tank (21), and an electric motor (22). In the air-cooled unit thermal system (1), the boiler (3), high-pressure cylinder (4), medium-pressure cylinder (5), low-pressure cylinder (6), condenser (13), condensate pump (12), low-pressure heater (11), deaerator (10), feed water pump (9), and high-pressure heater (8) are connected in series to form a loop. The high-pressure cylinder (4), medium-pressure cylinder (5), low-pressure cylinder (6), and generator (7) are connected in series. The steam extraction ports of the high-pressure cylinder (4) and medium-pressure cylinder (5) are connected to the high-pressure heater (8), and the steam extraction ports of the medium-pressure cylinder (5) and low-pressure cylinder (6) are connected to the low-pressure heater (11). In the heat pump system (2), the filter (14), regenerator (15), compressor (16), condenser (17), and expander (18) are connected in sequence. The condenser (17), heat storage tank (19), heat exchanger (20), and cold storage tank (21) are connected in series to form a loop. One end of the compressor (16) is connected to the motor (22), and the other end is connected to the expander (18). The boiler (3) is used to send steam into the high-pressure cylinder (4) to do work. The high-pressure cylinder (4) is used to reduce the pressure and temperature of the steam to the level required by the intermediate-pressure cylinder (5) and send the steam into the intermediate-pressure cylinder (5) to do work. The intermediate-pressure cylinder (5) is used to reduce the pressure and temperature of the steam to the level required by the low-pressure cylinder (6) and send the steam into the low-pressure cylinder (6) to do work. The low-pressure cylinder (6) is used to drive the generator (7) to generate electricity. The high-pressure heater (8) uses the steam drawn from the high-pressure cylinder (4) and the intermediate-pressure cylinder (5) to heat the feedwater. The boiler is equipped with a heating system; a deaerator (10) is used to remove oxygen from the feedwater to ensure the quality of the feedwater; a feedwater pump (9) is used to increase the feedwater pressure to meet the boiler feedwater requirements; a low-pressure heater (11) uses steam drawn from the intermediate-pressure cylinder (5) and the low-pressure cylinder (6) to heat the condensate; a condenser (13) is used to condense the steam from the low-pressure cylinder (6) into water and to establish and maintain a vacuum at the exhaust of the low-pressure cylinder (6); and a condensate pump (12) is used to pressurize the condensate at the outlet of the condenser (13) and send it to the regenerative cycle. The condenser (17) is used to exchange heat between the two streams of hot and cold working fluid from the outlet of the heat exchanger (20) and the outlet of the compressor (16); the regenerator (15) is used to exchange heat between the two streams of hot and cold working fluid from the outlet of the filter (14) and the outlet of the condenser (17); the heat storage tank (19) is used to store the hot molten salt after heat exchange in the condenser (17) and output heat when there is a heat demand; the cold storage tank (21) is used to store the cold molten salt after heat exchange; the heat exchanger (20) is used to exchange heat between the working fluid from the outlet of the heat storage tank (19) and the condensate, and the working fluid after heat exchange returns to the air-cooled unit thermal system (1) to form a closed loop; the expander (18) is used to recover the waste heat of the circulating working fluid at the outlet of the regenerator (15); The air from the outlet of the condenser (13) is filtered by the filter (14) and then enters the regenerator (15). After exchanging heat with the circulating working fluid at the outlet of the condenser (17), it enters the compressor (16) for pressurization. Then it enters the condenser (17) and exchanges heat with the condensate at the outlet of the heat exchanger (20). After that, it flows into the regenerator (15) for secondary heat exchange and then enters the expander (18) to form a cycle. After being expanded by the expander (18), the air becomes superheated steam and is discharged into the atmosphere.

2. The heat pump and thermal storage coupling system for waste heat recovery from exhaust steam in a coal-fired power plant according to claim 1, characterized in that, The heat pump system (2) is an air-type heat pump that uses a portion of the low-temperature hot air from the outlet of the condenser (13) as the circulating working fluid of the heat pump system (2).

3. The heat pump and thermal storage coupling system for waste heat recovery from exhaust steam in a coal-fired power plant according to claim 1, characterized in that, The electrical energy required by the electric motor (22) is generated by the generator (7).

4. The heat pump and thermal storage coupling system for recovering waste heat from exhaust steam in a coal-fired power plant according to claim 1, characterized in that, The heat storage medium is molten salt. During heat storage, the cold molten salt in the cold storage tank (21) is heated by the heat pump system (2) to become hot molten salt and stored in the heat storage tank (19). When releasing heat, the heat pump system (2) stops running. The hot molten salt in the heat storage tank (19) exchanges heat through the heat exchanger (20) and returns to the cold storage tank (21) to form a closed loop, realizing the recycling of molten salt.

5. The heat pump and thermal storage coupling system for recovering waste heat from exhaust steam in a coal-fired power plant according to claim 1, characterized in that, The cold flow entering the heat exchanger (20) comes from the condensate after the outlet of the feed water pump (9) and before the inlet of the high-pressure heater (8).

6. The heat pump and thermal storage coupling system for recovering waste heat from exhaust steam in a coal-fired power plant according to claim 1, characterized in that, The air entering the regenerator (15) is filtered by a filter (14) to remove dust, fine particles, impurities or contaminants from the air, so as to avoid blockage or corrosion of the regenerator (15), thereby improving the efficiency and life of the equipment and ensuring the normal operation of the heat pump system (2).

7. The heat pump and thermal storage coupling system for waste heat recovery from exhaust steam in a coal-fired power plant according to claim 1, characterized in that, The extraction port of the intermediate pressure cylinder (5) is connected to the deaerator (10).

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