Solar thermal power generation and high-temperature heat pump coupling operation method and coupling system

Abstract

The invention relates to the technical field of electric heating energy storage, and discloses a coupling operation method and a coupling system for solar thermal power generation and a high-temperature heat pump. The method comprises the steps that low-temperature extraction steam of a steam turbine generator unit is used as a low-temperature heat source, and wind power photovoltaic surplus electric energy and heat energy of the low-temperature heat source are converted into medium-temperature heat energy together through a high-temperature heat pump system and stored in medium-temperature fused salt; then the medium-temperature fused salt is heated to the high temperature needed by power generation through the solar light condensation and heat collection system and stored; and finally, steam generated by the high-temperature fused salt drives a steam turbine generator unit to generate power. The fused salt heating process of the high-temperature heat pump and the fused salt heating process of the solar heat collector are mutually independent, and independent control and connection are achieved through the medium-temperature fused salt tank. Through gradient utilization and control of energy, the solar heat collection area and investment cost are reduced, fluctuating abandoned electricity is efficiently consumed, unit waste heat is recycled, and the continuous power supply capacity, the operation efficiency and the power grid peak regulation flexibility of a photo-thermal power station are improved.

Description

Technical Field

[0001] This invention relates to the field of electrothermal energy storage technology, specifically to a method and system for coupled operation of solar thermal power generation and high-temperature heat pump. Background Technology

[0002] Solar thermal power generation technology, due to its unique advantage of achieving continuous and stable power generation through thermal storage, is considered an important clean power source for establishing new power systems. The main bottleneck for the large-scale development of solar thermal power generation technology lies in the high initial investment in its concentrating solar collector system and the fact that its power generation capacity is limited by sunshine conditions. Although thermal storage systems can generate electricity continuously after sunset, the storage capacity is usually limited, making it difficult to support longer periods of cloudy or rainy days or meet deep grid peak-shaving needs. Furthermore, in new energy bases where wind and solar power capacity is rapidly increasing, there is a large amount of "curtailed wind and solar" electricity. Currently, solar thermal power generation systems cannot directly and efficiently utilize this zero-cost but fluctuating electricity to supplement or expand their thermal storage capacity.

[0003] Among related technologies, large-scale electrothermal conversion and energy storage technologies, represented by high-temperature heat pumps, have attracted attention due to their large energy storage capacity, long cycle, flexible site selection, and high safety. They can efficiently convert electrical energy into high-temperature thermal energy for storage. However, in the "electricity-heat-electricity" cycle, the overall efficiency of independent high-temperature heat pump energy storage systems is limited by the upper limit temperature of the thermodynamic cycle. They usually require the consumption of high-quality electrical energy, and in the absence of low-cost high-temperature heat sources, their economic viability as independent energy storage power stations faces challenges.

[0004] Therefore, how to improve the continuous and stable power generation capacity, grid peak-shaving flexibility and operating efficiency of solar thermal power plants without significantly increasing the investment and area of ​​solar concentrating solar thermal systems, and how to achieve efficient conversion and storage of abandoned electricity generated by fluctuating new energy sources such as wind power and photovoltaics, has become an urgent problem to be solved. Summary of the Invention

[0005] In view of this, the present invention provides a method and system for coupled operation of solar thermal power generation and high-temperature heat pump to solve the problems mentioned in the background art.

[0006] In a first aspect, the present invention provides a method for coupled operation of solar thermal power generation and a high-temperature heat pump, the method comprising: The low-temperature extracted steam from the steam turbine generator set is used as a low-temperature heat source. The electrical energy and the heat energy of the low-temperature heat source are converted into medium-temperature heat energy through a high-temperature heat pump system and stored in medium-temperature molten salt. The electrical energy is the surplus electricity from wind and solar power. Molten salt containing the aforementioned medium-temperature thermal energy is heated to the high temperature required for power generation using a solar concentrating solar collector system and then stored. Steam is generated using the high-temperature molten salt to drive the steam turbine generator set to generate electricity; The high-temperature heat pump system and the solar concentrating solar collector can heat the molten salt independently, and the high-temperature heat pump system and the solar concentrating solar collector share the medium-temperature molten salt as an intermediate heat storage medium.

[0007] Beneficial Effects: This application achieves cascaded energy utilization and time-separated energy transfer by coupling a high-temperature heat pump system with a solar concentrating collector system in series and using a shared medium-temperature molten salt as the intermediate heat storage medium. The high-temperature heat pump can utilize surplus and abandoned power from wind and solar power, as well as the low-temperature waste heat from steam turbine generators, to preheat the molten salt to a medium temperature, reducing the heat load required by the solar collector system. This allows for a reduction in the concentrating collector area for the same power generation scale, lowering the investment and operating costs of the solar thermal system. It also converts previously abandoned wind and solar power into stable thermal energy storage, effectively mitigating and efficiently utilizing fluctuating power sources. The combination of heat pump preheating and solar heating overcomes the bottleneck of a single heat pump failing to reach the high temperatures required for power generation and compensates for the complete dependence of solar thermal power generation on sunlight, enabling the power plant to have longer-term heat storage and wider load regulation capabilities, thus enhancing the grid's peak-shaving adaptability.

[0008] In some embodiments, using the low-temperature extracted steam from the steam turbine generator set as a low-temperature heat source includes: When the steam turbine generator set is operating at low load or back pressure, a portion of its exhaust steam is extracted or extracted and used to heat cold water from the low-temperature water storage tank through the first heat exchanger to generate high-temperature water, which is then stored in the high-temperature water storage tank. The high-temperature water in the high-temperature water storage tank serves as the low-temperature heat source for the high-temperature heat pump system.

[0009] Beneficial effects: By recovering the waste heat from the low-temperature exhaust steam and extraction steam of the steam turbine generator set during low-load or back-pressure operation, the water in the storage tank is heated. This design not only effectively utilizes the low-grade heat energy that was originally difficult to utilize in the steam turbine cycle, which is conducive to improving thermal efficiency, but also provides a stable and controllable low-temperature heat source for high-temperature heat pumps, enhancing the economy and stability of heat pump operation.

[0010] In some embodiments, the high-temperature heat pump system uses air as the circulating working fluid, and the operating steps of the high-temperature heat pump system include: Air is compressed into a high-temperature, high-pressure state by a compressor; High-temperature, high-pressure air exchanges heat with low-temperature molten salt from a low-temperature molten salt tank in a high-temperature heat exchanger, heating the low-temperature molten salt to a medium temperature while the air is cooled. After being cooled, the air is cooled down at the hot end of the regenerator and then enters the expander to expand and do work, becoming low-temperature, low-pressure air. The low-temperature, low-pressure air exchanges heat with high-temperature water from a high-temperature water storage tank in a low-temperature heat exchanger. After absorbing heat, the air's temperature rises, while simultaneously cooling the high-temperature water. The heated air flows through the cold end of the regenerator, absorbs heat, and then returns to the compressor inlet, completing the cycle.

[0011] Beneficial effects: This solution uses air as the circulating working fluid, avoiding the environmental and safety issues that may arise from using special refrigerants; the installed regenerator can recover heat within the high-temperature heat pump system, increasing the compressor's intake temperature and improving the heat pump's performance; simultaneously, the expander's work process can partially recover energy to assist in driving the compressor or generating electricity, further optimizing system energy consumption; this design enables the high-temperature heat pump to efficiently convert the thermal energy of low-grade hot water into the thermal energy of medium-grade medium-temperature molten salt.

[0012] In some embodiments, heating the low-temperature molten salt to a medium temperature means heating the molten salt to a temperature range of 400°C to 480°C; The heating via a solar concentrating thermal system involves heating the molten salt from a medium temperature to a temperature range of 530°C to 580°C.

[0013] Beneficial effects: Setting the heating target of the heat pump at 400℃~480℃ and the heating target of the solar thermal collector at 530℃~580℃, this temperature range is the optimal operating temperature for molten salt solar thermal power generation; by using a phased and zoned heating method, good working efficiency is ensured. The heat pump avoids the sharp drop in efficiency caused by pursuing excessively high temperatures, while the solar thermal collector is used to achieve a higher energy quality, thus maximizing overall efficiency and achieving a balance between technical and economic efficiency.

[0014] In some embodiments, when the power grid requires peak shaving or the use of a low-temperature heat source, the turbine generator set is controlled to enter a cylinder-cutting operation mode, and a portion of the low-pressure cylinders are disengaged from the rotor via a clutch, so that the exhaust steam serves as a low-temperature heat source for the high-temperature heat pump system.

[0015] Beneficial effects: When the power grid requires deep peak shaving by the generator units or when there is a large amount of recoverable waste heat, disengaging part of the low-pressure cylinder by the clutch allows the steam turbine generator unit to operate at a higher back pressure, thereby generating more exhaust steam at a more suitable temperature as a low-temperature heat source. This method can reduce the minimum active power output of the unit, broaden the load regulation range, and maximize the utilization of the latent heat of the turbine exhaust steam, providing a sufficient heat source for high-temperature heat pumps. This scheme can maximize the conversion and storage capacity of abandoned electricity and waste heat, and can fully realize the value of the system in extreme peak shaving scenarios.

[0016] Secondly, the present invention also provides a solar thermal power generation and high-temperature heat pump coupling system, comprising: The energy storage subsystem includes a high-temperature molten salt tank, a steam generation system, a low-temperature molten salt tank, a high-temperature heat pump unit, a medium-temperature molten salt tank, and a solar concentrating collector unit, which are connected sequentially through pipelines to form a molten salt circulation loop. The outlet of the high-temperature molten salt tank is connected to the molten salt side inlet of the steam generation system, the molten salt side outlet of the steam generation system is connected to the inlet of the low-temperature molten salt tank, the outlet of the low-temperature molten salt tank is connected to the inlet of the medium-temperature molten salt tank through the high-temperature heat pump unit, and the outlet of the medium-temperature molten salt tank is connected to the inlet of the high-temperature molten salt tank through the solar concentrating collector unit. The power generation system includes a steam turbine generator set, whose steam inlet is connected to the steam-side outlet of the steam generation system via a main steam pipeline, and whose exhaust end is connected to a condenser; the condenser is connected back to the feedwater-side inlet of the steam generation system via a feedwater system. The low-temperature heat source subsystem includes a high-temperature water storage tank and a low-temperature water storage tank, which are connected by pipelines and pumps to form a water circulation loop, and exchange heat with the steam extraction pipeline and exhaust pipeline of the steam turbine generator set through a water storage heat exchanger. The high-temperature heat pump unit includes a low-temperature heat exchanger, the heat source side of which is connected to the water circulation loop between the high-temperature water storage tank and the low-temperature water storage tank.

[0017] Beneficial Effects: The coupled system integrates the energy storage subsystem, the power generation subsystem, and the low-temperature heat source subsystem. Specifically, the molten salt circulation loop of the energy storage subsystem is designed to flow sequentially through a high-temperature molten salt tank, a steam generation system, a low-temperature molten salt tank, a high-temperature heat pump unit, a medium-temperature molten salt tank, and a solar concentrating collector unit. After releasing heat to generate electricity, the molten salt becomes low-temperature molten salt. The high-temperature heat pump unit uses electricity and recovered low-temperature heat to raise it to a medium-temperature state and store it in the medium-temperature molten salt tank. Then, the solar concentrating collector unit further heats it to the high-temperature state required for power generation. This series design of heat pump preheating and solar precise heating eliminates the need for the solar collector system to heat the molten salt from ambient temperature, reducing its heat load. To achieve the same power generation capacity and heat storage duration, the required concentrating collector area can be significantly reduced, directly lowering the system's solar thermal power generation cost. The low-temperature heat source subsystem is connected to the extraction and exhaust pipes of the steam turbine generator set via a water storage heat exchanger. It actively recovers the waste heat from the low-temperature steam generated by the steam turbine generator set under low-load operating modes, converting it into heat energy in the high-temperature water storage tank. The high-temperature water exchanges heat through the low-temperature heat exchanger, providing a stable and controllable low-temperature heat source for the high-temperature heat pump unit. The high-temperature heat pump unit utilizes both wind and solar power curtailment from the grid and the recovered waste heat from the low-temperature heat source subsystem. The system can utilize both individually or simultaneously. At night or when there is no sunlight, it can operate the heat pump for heat storage using inexpensive curtailed electricity and steam turbine waste heat, and then use solar energy for final heating during the day. By converting this low-grade energy into heat energy from medium-temperature molten salt for storage, the overall energy utilization efficiency is improved, and a low-cost or zero-cost heat source is provided for the operation of the high-temperature heat pump, overcoming its poor economic performance when operating independently. Furthermore, this type of storage and power generation has good independence in terms of time, which also enables the power generation part to flexibly respond to the peak control of the power grid: during the off-peak hours, more heat can be stored and less or no power can be generated; during the peak hours, the stored heat energy can be used to generate power at full load. This scheme effectively extends the continuous power supply duration and load regulation range of the solar thermal power plant.

[0018] In some embodiments, the high-temperature heat pump unit further includes a compressor, a high-temperature heat exchanger, a regenerator, and an expander; The compressor outlet is connected to the working fluid side inlet of the high-temperature heat exchanger, the working fluid side outlet of the high-temperature heat exchanger is connected to the hot end inlet of the regenerator, the hot end outlet of the regenerator is connected to the expander inlet, the expander outlet is connected to the working fluid side inlet of the low-temperature heat exchanger, the working fluid side outlet of the low-temperature heat exchanger is connected to the cold end inlet of the regenerator, and the cold end outlet of the regenerator is connected back to the compressor inlet, forming a heat pump circulation loop with air as the working fluid; the heat source side of the high-temperature heat exchanger is connected in series in the molten salt pipeline between the low-temperature molten salt tank and the medium-temperature molten salt tank.

[0019] Beneficial Effects: This scheme uses air as the circulating working fluid, resulting in high system safety and environmental friendliness. The compressor, high-temperature heat exchanger, regenerator, expander, and low-temperature heat exchanger are connected sequentially to form a complete closed thermodynamic cycle. Through continuous processing steps—compression heating, high-temperature heat release to heat the molten salt, heat recovery, expansion cooling, low-temperature heat absorption, and regenerator preheating—a highly efficient heat transfer path is achieved. The regenerator recovers the residual cooling energy of the air after expansion, which is used to precool the air before it enters the expander and preheat the air returning to the compressor, improving the coefficient of performance of the heat pump cycle. The expander can recover some of the expansion work to assist in driving the compressor, further reducing energy consumption. The high-temperature heat exchanger, connected in series in the molten salt loop, ensures direct and efficient heat transfer. The connection layout between the various devices reduces pipeline heat loss and improves response speed.

[0020] In some embodiments, the steam turbine generator set includes at least one high-pressure cylinder and at least one low-pressure cylinder; a clutch is provided on the steam inlet pipe of the low-pressure cylinder or on the connecting shaft between the low-pressure cylinder and the high-pressure cylinder, the clutch being used to realize the engagement and disengagement of the low-pressure cylinder.

[0021] Beneficial effects: The clutch allows the low-pressure cylinder to flexibly engage or disengage from the rotor. When the power grid requires deep peak shaving or maximizes waste heat recovery, the clutch can be disengaged, allowing the unit to enter cylinder-cutting or high back-pressure operation modes. The increased exhaust pressure and temperature of the turbine generator set, along with the increased exhaust volume and quality, make it more suitable as a heat source for heat pumps. This reduces the unit's minimum active power generation, broadens the load regulation range, and maximizes the utilization of the latent heat of the turbine exhaust, providing a sufficient heat source for high-temperature heat pumps.

[0022] In some embodiments, the solar concentrating solar collector unit may be configured as a tower concentrating solar collector system, a trough concentrating solar collector system, or a linear Fresnel concentrating solar collector system.

[0023] Beneficial effects: Tower-type concentrating solar thermal systems offer advantages such as high concentration ratio and high operating temperature, more efficiently heating medium-temperature molten salt to the target temperature, and exhibiting high photoelectric conversion efficiency. Trough-type concentrating solar thermal systems offer advantages in reliability and deployment flexibility, making them suitable for applications with limited terrain. Linear Fresnel-type concentrating solar thermal systems offer advantages such as low initial investment and good terrain adaptability.

[0024] In some embodiments, at least two flow paths are connected in parallel between the high-temperature water storage tank and the low-temperature water storage tank, one of which is provided with the water storage heat exchanger and the other is provided with the low-temperature heat exchanger.

[0025] Beneficial effects: One path connects to the steam turbine generator set via a water storage heat exchanger for recovering and storing waste heat from the steam. The other path connects to a high-temperature heat pump unit via a low-temperature heat exchanger to release the stored heat to drive the heat pump. The recovery and storage of waste heat from the steam turbine generator set is independent of the heat pump, and the operation of the heat pump is also independent of the steam turbine generator set. This high degree of independence between the two operations makes system control more flexible and effectively improves the overall system's freedom in energy dispatch. For example, during periods of low grid load and when the steam turbine generator set is operating at low load, waste heat can be fully recovered and stored in a hot water tank. During peak periods of power curtailment, the stored hot water can be used to drive the heat pump, combined with electrical energy, to maximize energy storage. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific 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 from these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the solar thermal power generation and high-temperature heat pump coupling system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the steam generation system in the solar thermal power generation and high-temperature heat pump coupling system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the water supply system in the solar thermal power generation and high-temperature heat pump coupling system of an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: 101. High-temperature molten salt tank; 102. Steam generation system; 103. Low-temperature molten salt tank; 1041. Low-temperature heat exchanger; 1042. Compressor; 1043. High-temperature heat exchanger; 1044. Regenerator; 1045. Expander; 105. Medium-temperature molten salt tank; 106. Solar concentrator; 2011. High-pressure cylinder; 2012. Low-pressure cylinder; 202. Condenser; 203. Water supply system; 301. High-temperature water storage tank; 302. Low-temperature water storage tank; 303. Water storage heat exchanger. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] The following is combined with Figures 1 to 3 The following describes embodiments of the present invention.

[0031] According to an embodiment of the present invention, in one aspect, a solar thermal power generation and high-temperature heat pump coupling system is provided, including an energy storage subsystem, a power generation system and a low-temperature heat source subsystem.

[0032] like Figure 1 As shown, the energy storage subsystem includes a high-temperature molten salt tank 101, a steam generation system 102, a low-temperature molten salt tank 103, a high-temperature heat pump unit, a medium-temperature molten salt tank 105, and a solar concentrating collector unit 106, which are connected in sequence through pipelines to form a molten salt circulation loop. The outlet of the high-temperature molten salt tank 101 is connected to the molten salt side inlet of the steam generation system 102, the molten salt side outlet of the steam generation system 102 is connected to the inlet of the low-temperature molten salt tank 103, the outlet of the low-temperature molten salt tank 103 is connected to the inlet of the medium-temperature molten salt tank 105 through the high-temperature heat pump unit, and the outlet of the medium-temperature molten salt tank 105 is connected to the inlet of the high-temperature molten salt tank 101 through the solar concentrating collector unit 106.

[0033] The power generation system includes a steam turbine generator set, whose steam inlet is connected to the steam side outlet of the steam generation system 102 through the main steam pipeline, and whose exhaust end is connected to the condenser 202; the condenser 202 is connected back to the feedwater side inlet of the steam generation system 102 through the feedwater system 203, thereby forming a steam-water cycle.

[0034] like Figure 1 As shown, the low-temperature heat source subsystem includes a high-temperature water storage tank 301 and a low-temperature water storage tank 302. The two are connected by pipelines and pumps to form a water circulation loop. The water storage heat exchanger 303 exchanges heat with the steam extraction pipeline and exhaust pipeline of the steam turbine generator set, thereby transferring the waste heat of the low-temperature steam on the turbine side to the water in the water loop, realizing the recovery and storage of heat energy.

[0035] The coupling system provided in this embodiment integrates the energy storage subsystem, the power generation subsystem, and the low-temperature heat source subsystem. Specifically, the molten salt circulation loop of the energy storage subsystem is designed to flow sequentially through a high-temperature molten salt tank 101, a steam generation system 102, a low-temperature molten salt tank 103, a high-temperature heat pump unit, a medium-temperature molten salt tank 105, and a solar concentrator unit 106. The steam generation system 102 serves as the energy release point, the high-temperature heat pump unit as the first-stage energy boosting point, the medium-temperature molten salt tank 105 as the intermediate energy storage point, the solar concentrator unit 106 as the second-stage energy boosting point, and the high-temperature molten salt tank 101 as the energy storage endpoint. After releasing heat to generate electricity, the molten salt becomes low-temperature molten salt. The high-temperature heat pump unit uses electricity and recovered low-temperature heat to raise it to a medium-temperature state and store it in the medium-temperature molten salt tank 105. Then, the solar concentrator unit 106 further heats it to the high-temperature state required for power generation. This series design of heat pump preheating and solar precise heating eliminates the need for the solar thermal system to heat molten salt from ambient temperature, reducing its heat load. To achieve the same power generation capacity and heat storage duration, the required concentrating area can be significantly reduced, directly lowering the system's solar thermal power generation cost. The low-temperature heat source subsystem is connected to the extraction and exhaust pipes of the steam turbine generator set via a water storage heat exchanger 303, enabling it to actively recover the waste heat from the low-temperature steam generated by the steam turbine generator set under low-load operating modes and convert it into heat energy in the high-temperature water storage tank 301.

[0036] The coupled system provided in this embodiment utilizes both wind and solar power curtailment from the grid and waste heat recovered from a low-temperature heat source subsystem. The system can utilize both independently or simultaneously. At night or when there is no sunlight, the heat pump can operate using inexpensive curtailed electricity and turbine waste heat for heat storage, and then utilize solar energy for final heating during the day. This low-grade energy is converted into medium-temperature molten salt heat energy for storage, improving overall energy efficiency and providing a low-cost or zero-cost heat source for the high-temperature heat pump, thus mitigating its poor economic viability when operating independently. Furthermore, this storage and power generation are highly independent in time, allowing the power generation section to flexibly respond to grid peak-shaving control: during periods of low electricity demand, more heat can be stored, less power generation can be generated, or even no power generation can be achieved; during peak electricity demand, the stored heat energy can be used to generate power at full load. This embodiment effectively extends the continuous power supply duration and load regulation range of the solar thermal power plant.

[0037] In one exemplary implementation, such as Figure 1As shown, the high-temperature heat pump unit includes a low-temperature heat exchanger 1041, a compressor 1042, a high-temperature heat exchanger 1043, a regenerator 1044, and an expander 1045; the heat source side of the low-temperature heat exchanger 1041 is connected to the water circulation loop between the high-temperature water storage tank 301 and the low-temperature water storage tank 302; the high-temperature water exchanges heat through the low-temperature heat exchanger 1041, which can provide a stable and controllable low-temperature heat source for the high-temperature heat pump unit. The outlet of compressor 1042 is connected to the working fluid side inlet of high-temperature heat exchanger 1043. The working fluid side outlet of high-temperature heat exchanger 1043 is connected to the hot end inlet of regenerator 1044. The hot end outlet of regenerator 1044 is connected to the inlet of expander 1045. The outlet of expander 1045 is connected to the working fluid side inlet of low-temperature heat exchanger 1041. The working fluid side outlet of low-temperature heat exchanger 1041 is connected to the cold end inlet of regenerator 1044. The cold end outlet of regenerator 1044 is connected back to the inlet of compressor 1042, forming a heat pump cycle loop with air as the working fluid. The heat source side of high-temperature heat exchanger 1043 is connected in series in the molten salt pipeline between low-temperature molten salt tank 103 and medium-temperature molten salt tank 105, so that the high-temperature heat generated by compression in the heat pump cycle can be directly used to heat the molten salt. This scheme connects compressor 1042, high-temperature heat exchanger 1043, regenerator 1044, expander 1045, and low-temperature heat exchanger 1041 sequentially, forming a complete closed thermodynamic cycle. Through continuous processing steps—compression heating, high-temperature heat release to heat molten salt, heat recovery, expansion cooling, low-temperature heat absorption, and regeneration preheating—a highly efficient heat energy transfer path is achieved. This scheme uses air as the circulating working fluid, resulting in high system safety and environmental friendliness.

[0038] In the specific workflow, air is compressed and heated in compressor 1042; the high-temperature and high-pressure air enters high-temperature heat exchanger 1043, where it exchanges heat with cold molten salt from low-temperature molten salt tank 103, transferring heat to the molten salt and raising its temperature, while the air itself is cooled; the cooled air flows through the hot end of regenerator 1044, further releasing residual heat and cooling down; then it enters expander 1045 to expand and do work, causing a sharp drop in pressure and temperature, becoming low-temperature and low-pressure air; this low-temperature and low-pressure air enters low-temperature heat exchanger 1041, absorbing heat from the hot water in high-temperature water storage tank 301, raising its temperature; the heated air then flows through the cold end of regenerator 1044, absorbing heat from the hot end air and being preheated, finally returning to the inlet of compressor 1042, completing one cycle.

[0039] This design utilizes a regenerator 1044 to recover residual cooling from the expanded air, which is then used to pre-cool the air before it enters the expander 1045 and preheat the air returning to the compressor 1042, thus improving the coefficient of performance of the heat pump cycle. The expander 1045 can recover some of the expansion work to assist in driving the compressor 1042, further reducing energy consumption. The high-temperature heat exchanger 1043 is connected in series in the molten salt circuit, ensuring direct and efficient heat transfer. The interconnected layout of the various devices reduces pipeline heat loss and improves response speed.

[0040] In one specific embodiment, the solar concentrating collector unit 106 is configured as a tower-type concentrating solar collector system, which includes a heliostat field located on the ground side and a receiver located at the top of the tower. The outlet of the medium-temperature molten salt tank 105 is connected to the inlet of the receiver via a molten salt pump and a riser pipe, and the outlet of the receiver is connected to the inlet of the high-temperature molten salt tank 101 via a downcomer pipe. The tower-type concentrating solar collector system has the advantages of high concentration ratio and high operating temperature, and can heat the medium-temperature molten salt to the target temperature more efficiently, resulting in higher photoelectric conversion efficiency.

[0041] In another embodiment, the solar concentrating collector unit 106 is configured as a trough-type concentrating collector system, which includes rows of parabolic trough reflectors and vacuum collector tubes located on their focal lines. The outlet of the medium-temperature molten salt tank 105 is connected to the inlet of the vacuum collector tubes via a molten salt pump and pipeline, and the outlet of the vacuum collector tubes is connected to the inlet of the high-temperature molten salt tank 101 via pipeline. The trough-type concentrating collector system has the advantages of reliability and deployment flexibility, and is suitable for occasions where terrain conditions are limited.

[0042] In the third embodiment, the solar concentrating collector unit 106 is configured as a linear Fresnel concentrating collector system, which includes a multi-row planar reflector array capable of uniaxial rotation and a receiving device located at the height of their common focal line. The reflectors reflect sunlight to the fixed receiving device, which contains a vacuum collector tube through which molten salt flows. Molten salt from the medium-temperature molten salt tank 105 is pumped into the vacuum collector tube, heated to the high temperature required for power generation by focused solar radiation, and then transported to the high-temperature molten salt tank 101 for storage. The linear Fresnel concentrating collector system has advantages such as low initial investment and good terrain adaptability.

[0043] In specific implementation methods, such as Figure 1As shown, the steam turbine generator set includes at least one high-pressure cylinder 2011 and at least one low-pressure cylinder 2012. A clutch (not shown in the figure) is installed on the steam inlet pipe of the low-pressure cylinder 2012, or on the connecting shaft between the low-pressure cylinder 2012 and the high-pressure cylinder 2011. The clutch is used to engage and disengage the low-pressure cylinder 2012. The clutch allows the low-pressure cylinder 2012 to flexibly engage or disengage from the turbine rotor. When the grid requires deep peak shaving or needs to maximize the recovery and utilization of waste heat, the clutch can be disengaged, allowing the unit to enter a cylinder-cutting or high back-pressure operation mode. In this mode, the exhaust steam from the high-pressure cylinder 2011 of the steam turbine no longer enters the low-pressure cylinder 2012 for expansion, but is directly discharged at a higher pressure and temperature. The exhaust steam pressure and temperature of the steam turbine generator set increase, the exhaust steam volume increases, and the quality is more suitable as a heat source for heat pumps. This reduces the minimum active power of the unit, widens the load regulation range, and maximizes the utilization of the latent heat of the turbine exhaust steam, providing a sufficient heat source for high-temperature heat pumps.

[0044] In one specific implementation, the clutch is configured as a synchronous self-disengaging clutch.

[0045] In a specific implementation, at least two flow paths are connected in parallel between the high-temperature water storage tank 301 and the low-temperature water storage tank 302. One path is equipped with a water storage heat exchanger 303, and the other path is equipped with a low-temperature heat exchanger 1041. This parallel design enables independent control of the two processes of low-temperature heat source heat storage and energy supply. Specifically, one path connects to the steam turbine generator set via the water storage heat exchanger 303 for recovering and storing waste heat from the steam, while the other path connects to the high-temperature heat pump unit via the low-temperature heat exchanger 1041 to release the stored heat to drive the heat pump. The recovery and storage of waste heat from the steam turbine generator set is not constrained by the heat pump, and the operation of the heat pump is not constrained by the steam turbine generator set. The two operations are highly independent, making system control more flexible and effectively improving the freedom of energy dispatch for the entire system. For example, during periods of low grid load and low-load operation of the steam turbine generator set, waste heat can be fully recovered and stored in the hot water tank; during peak periods of power curtailment, the stored hot water can be used to drive the heat pump, combined with electrical energy, to maximize energy storage.

[0046] In specific implementation methods, such as Figure 2 As shown, the steam generation system 102 can be configured as a multi-stage heat exchanger structure, including a preheater, an evaporator, a superheater, and optionally a reheater. High-pressure feedwater from the feedwater system 203 flows sequentially through the preheater and evaporator, is heated by molten salt into saturated steam, and then heated by the reheater into high-temperature, high-pressure superheated steam, which is then sent to the high-pressure cylinder 2011 of the turbine generator set to perform work. The steam discharged from the high-pressure cylinder 2011 can return to the reheater, be reheated by molten salt, and then enter the intermediate and low-pressure cylinders 2012 of the turbine to continue expanding and performing work.

[0047] In specific implementation methods, such as Figure 3 As shown, the feedwater system 203 includes multiple low-pressure heaters, a deaerator, and multiple high-pressure heaters connected in sequence. The condensate from the condenser 202 is initially heated by the low-pressure heater group, then enters the deaerator to remove dissolved oxygen. After being pressurized by the feedwater pump, it is further heated to a predetermined temperature by the high-pressure heater group and finally sent to the steam generation system 102.

[0048] According to an embodiment of the present invention, in another aspect, a method for coupled operation of solar thermal power generation and high-temperature heat pump is also provided, the coupled operation method comprising: The low-temperature extracted steam from the steam turbine generator set is used as a low-temperature heat source. The electrical energy and the heat energy of the low-temperature heat source are converted into medium-temperature heat energy through a high-temperature heat pump system and stored in medium-temperature molten salt. The electrical energy is the surplus electricity from wind and solar power. Molten salt containing medium-temperature thermal energy is heated to the high temperature required for power generation using a solar concentrating solar collector system and then stored. Steam is generated using high-temperature molten salt to drive a steam turbine generator set to generate electricity; Among them, the heating process of molten salt by the high-temperature heat pump system and the heating process of molten salt by the solar concentrating solar collector system can be heated independently, and the high-temperature heat pump system and the solar concentrating solar collector system share a medium-temperature molten salt as an intermediate heat storage medium.

[0049] This application achieves cascaded energy utilization and time-separated energy transfer by coupling a high-temperature heat pump system in series with a solar concentrating solar collector system and using a shared medium-temperature molten salt as the intermediate heat storage medium. The high-temperature heat pump can utilize surplus and abandoned power from wind and solar power, as well as the low-temperature waste heat from steam turbine generators, to preheat the molten salt to a medium temperature, reducing the heat load required by the solar collector system. This allows for a reduction in the concentrating solar collector area for the same power generation scale, lowering the investment and operating costs of the solar thermal system. It also converts previously abandoned wind and solar power into stable thermal energy storage, effectively mitigating and efficiently utilizing fluctuating power sources. Through the combination of heat pump preheating and solar heating, it overcomes the bottleneck of a single heat pump failing to reach the high temperatures required for power generation and compensates for the complete dependence of solar thermal power generation on sunlight. This enables the power plant to have longer-term heat storage and wider load regulation capabilities, enhancing the grid's peak-shaving adaptability.

[0050] In a specific implementation, using the low-temperature extracted steam from the steam turbine generator set as a low-temperature heat source includes: When the steam turbine generator set is running at low load or back pressure, a portion of its exhaust steam or extraction steam is extracted and used to heat the cold water from the low-temperature water storage tank 302 through the first heat exchanger to generate high-temperature water, which is then stored in the high-temperature water storage tank 301. The high-temperature water in the high-temperature water storage tank 301 serves as the low-temperature heat source for the high-temperature heat pump system.

[0051] By recovering the waste heat from the low-temperature exhaust steam and extraction steam of the steam turbine generator set during low-load or back-pressure operation, the water in the storage tank is heated. This design not only effectively utilizes the low-grade heat energy that was originally difficult to utilize in the steam turbine cycle, which is conducive to improving thermal efficiency, but also provides a stable and controllable low-temperature heat source for high-temperature heat pumps, enhancing the economy and stability of heat pump operation.

[0052] In a specific implementation, the high-temperature heat pump system uses air as the circulating working fluid, and the operating steps of the high-temperature heat pump system include: Air is compressed into a high-temperature, high-pressure state by compressor 1042; High-temperature and high-pressure air exchanges heat with low-temperature molten salt from low-temperature molten salt tank 103 in high-temperature heat exchanger 1043, heating the low-temperature molten salt to medium temperature while the air is cooled. After being cooled, the air enters the expander 1045 to expand and do work, becoming low-temperature, low-pressure air after being cooled by the hot end of the regenerator 1044. Low-temperature, low-pressure air exchanges heat with high-temperature water from high-temperature water storage tank 301 in low-temperature heat exchanger 1041, absorbing heat and increasing in temperature, while cooling the high-temperature water. The heated air flows through the cold end of the regenerator 1044, absorbs heat, and then returns to the inlet of the compressor 1042, completing the cycle.

[0053] This design uses air as the circulating working fluid, avoiding the environmental and safety issues that may arise from using special refrigerants. The regenerator 1044 enables heat recovery within the high-temperature heat pump system, increasing the intake temperature of the compressor 1042 and improving the heat pump's performance. Simultaneously, the expansion unit 1045 can partially recover energy during its operation, assisting in driving the compressor 1042 or generating electricity, further optimizing system energy consumption. This design allows the high-temperature heat pump to efficiently convert the thermal energy of low-grade hot water into the thermal energy of medium-grade, medium-temperature molten salt.

[0054] In a specific implementation, heating the low-temperature molten salt to a medium temperature range of 400°C to 480°C; heating it using a solar concentrating solar collector system, which heats the molten salt from the medium temperature range to 530°C to 580°C. The low-temperature molten salt is defined as a temperature within 400°C.

[0055] This scheme sets the heating target of the heat pump at 400℃~480℃ and the heating target of the solar collector at 530℃~580℃. This temperature range is the optimal operating temperature for molten salt solar thermal power generation. By using a phased and zoned heating method, good working efficiency is ensured. The heat pump avoids the sharp drop in efficiency caused by pursuing excessively high temperatures, while the solar collector is used to achieve a higher energy quality, thus maximizing overall efficiency and achieving a balance between technical and economic efficiency.

[0056] In a specific implementation, when the power grid requires peak shaving or the use of a low-temperature heat source, the turbine generator set is controlled to enter the cylinder cutting operation mode. The clutch is used to disconnect part of the low-pressure cylinder 2012 from the rotor, so that the exhaust steam can be used as a low-temperature heat source for the high-temperature heat pump system.

[0057] When the power grid requires deep peak shaving by the generator units or when there is a large amount of recoverable waste heat, the turbine generator unit can operate at a higher back pressure by disengaging part of the low-pressure cylinder 2012 via a clutch, thereby generating more exhaust steam at a more suitable temperature as a low-temperature heat source. This method can reduce the minimum active power output of the unit, broaden the load regulation range, and maximize the utilization of the latent heat of the turbine exhaust steam, providing a sufficient heat source for high-temperature heat pumps. This scheme can maximize the conversion and storage capacity of abandoned power and waste heat, and can fully realize the value of the system in extreme peak shaving scenarios.

[0058] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for coupled operation of solar thermal power generation and high-temperature heat pump, characterized in that, The method includes: The low-temperature extracted steam from the steam turbine generator set is used as a low-temperature heat source. The electrical energy and the heat energy of the low-temperature heat source are converted into medium-temperature heat energy through a high-temperature heat pump system and stored in medium-temperature molten salt. The electrical energy is the surplus electricity from wind and solar power. Molten salt containing the aforementioned medium-temperature thermal energy is heated to the high temperature required for power generation using a solar concentrating solar collector system and then stored. Steam is generated using high-temperature molten salt to drive the steam turbine generator set to generate electricity; The high-temperature heat pump system and the solar concentrating solar collector can heat the molten salt independently, and the high-temperature heat pump system and the solar concentrating solar collector share the medium-temperature molten salt as an intermediate heat storage medium.

2. The coupled operation method according to claim 1, characterized in that, The use of low-temperature extracted steam from a steam turbine generator set as a low-temperature heat source includes: When the steam turbine generator set is running at low load or back pressure, a portion of its exhaust steam or extraction steam is extracted and heated by the first heat exchanger to generate high-temperature water from the low-temperature water storage tank (302), which is then stored in the high-temperature water storage tank (301). The high-temperature water in the high-temperature water storage tank (301) serves as the low-temperature heat source for the high-temperature heat pump system.

3. The coupled operation method according to claim 1 or 2, characterized in that, The high-temperature heat pump system uses air as the circulating working fluid, and the operating steps of the high-temperature heat pump system include: Air is compressed into a high-temperature, high-pressure state by the compressor (1042); High-temperature and high-pressure air exchanges heat with low-temperature molten salt from a low-temperature molten salt tank (103) in a high-temperature heat exchanger (1043), heating the low-temperature molten salt to a medium temperature while the air is cooled. After being cooled, the air is cooled down by the hot end of the regenerator (1044) and then enters the expander (1045) to expand and do work, becoming low-temperature and low-pressure air; The low-temperature, low-pressure air exchanges heat with high-temperature water from a high-temperature water storage tank (301) in a low-temperature heat exchanger (1041), absorbing heat and increasing in temperature, while simultaneously cooling the high-temperature water. The heated air flows through the cold end of the regenerator (1044), absorbs heat, and then returns to the inlet of the compressor (1042) to complete the cycle.

4. The coupled operation method according to claim 3, characterized in that, Heating low-temperature molten salt to medium temperature means heating molten salt to a temperature range of 400℃~480℃; The heating via a solar concentrating thermal system involves heating the molten salt from a medium temperature to a temperature range of 530°C to 580°C.

5. The coupled operation method according to claim 2, characterized in that, When the power grid requires peak shaving or the use of low-temperature heat sources, the turbine generator set is controlled to enter the cylinder cutting operation mode. The clutch is used to disengage part of the low-pressure cylinder (2012) from the rotor, so that the exhaust steam can be used as the low-temperature heat source of the high-temperature heat pump system.

6. A coupling system for implementing the method of any one of claims 1-5, comprising solar thermal power generation and a high-temperature heat pump, characterized in that, include: The energy storage subsystem includes a high-temperature molten salt tank (101), a steam generation system (102), a low-temperature molten salt tank (103), a high-temperature heat pump unit, a medium-temperature molten salt tank (105), and a solar concentrating collector unit (106), which are connected in sequence through pipelines to form a molten salt circulation loop. The outlet of the high-temperature molten salt tank (101) is connected to the molten salt side inlet of the steam generation system (102), the molten salt side outlet of the steam generation system (102) is connected to the inlet of the low-temperature molten salt tank (103), the outlet of the low-temperature molten salt tank (103) is connected to the inlet of the medium-temperature molten salt tank (105) through the high-temperature heat pump unit, and the outlet of the medium-temperature molten salt tank (105) is connected to the inlet of the high-temperature molten salt tank (101) through the solar concentrating collector unit (106). The power generation system includes a steam turbine generator set, whose steam inlet is connected to the steam-side outlet of the steam generation system (102) via a main steam pipeline, and whose exhaust end is connected to a condenser (202); the condenser (202) is connected back to the feedwater inlet of the steam generation system (102) via a feedwater system (203); The low-temperature heat source subsystem includes a high-temperature water storage tank (301) and a low-temperature water storage tank (302), which are connected by pipelines and pumps to form a water circulation loop, and exchange heat with the steam extraction pipeline and exhaust pipeline of the steam turbine generator set through a water storage heat exchanger (303); The high-temperature heat pump unit includes a low-temperature heat exchanger (1041), the heat source side of which is connected to the water circulation loop between the high-temperature water storage tank (301) and the low-temperature water storage tank (302).

7. The coupling system according to claim 6, characterized in that, The high-temperature heat pump unit also includes a compressor (1042), a high-temperature heat exchanger (1043), a regenerator (1044), and an expander (1045); The compressor (1042) outlet is connected to the working fluid side inlet of the high-temperature heat exchanger (1043), the working fluid side outlet of the high-temperature heat exchanger (1043) is connected to the hot end inlet of the regenerator (1044), the hot end outlet of the regenerator (1044) is connected to the inlet of the expander (1045), the outlet of the expander (1045) is connected to the working fluid side inlet of the low-temperature heat exchanger (1041), the working fluid side outlet of the low-temperature heat exchanger (1041) is connected to the cold end inlet of the regenerator (1044), and the cold end outlet of the regenerator (1044) is connected back to the compressor (1042) inlet, forming a heat pump circulation loop with air as the working fluid; the heat source side of the high-temperature heat exchanger (1043) is connected in series in the molten salt pipeline between the low-temperature molten salt tank (103) and the medium-temperature molten salt tank (105).

8. The coupling system according to claim 6, characterized in that, The steam turbine generator set includes at least one high-pressure cylinder (2011) and at least one low-pressure cylinder (2012); a clutch is provided on the steam inlet pipe of the low-pressure cylinder (2012) or on the connecting shaft between the low-pressure cylinder (2012) and the high-pressure cylinder (2011), the clutch being used to realize the engagement and disengagement of the low-pressure cylinder (2012).

9. The coupling system according to claim 6, characterized in that, The solar concentrating collector unit (106) is a tower, trough, or linear Fresnel concentrating collector system.

10. The coupling system according to claim 6, characterized in that, At least two flow paths are connected in parallel between the high-temperature water storage tank (301) and the low-temperature water storage tank (302), one of which is equipped with the water storage heat exchanger (303) and the other is equipped with the low-temperature heat exchanger (1041).

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