Supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization

Abstract

The invention provides a supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization, belongs to the technical field of supercritical carbon dioxide power generation systems, and can at least partially solve the problems that according to an existing carbon dioxide system, all cycles are designed independently, energy gradient utilization is insufficient, the energy storage regulation and control capacity is insufficient, and power generation efficiency is high. The system comprises a solar heat collection module, a carbon dioxide power cycle module, a waste heat power generation module and an energy storage heat exchange medium, solar high-temperature heat collection, supercritical carbon dioxide cycle and organic Rankine cycle are organically integrated, and multi-stage gradient utilization of energy is achieved; the system stores heat when illumination is sufficient and releases heat when illumination is insufficient or at night, stable output of power generation power is ensured, and the problem of intermittency of solar power generation is solved.

Description

Technical Field

[0001] This invention belongs to the technical field of supercritical carbon dioxide power generation systems, specifically relating to a supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization. Background Technology

[0002] With the continued growth of global energy demand and increasing environmental awareness, the development and utilization of renewable energy has become an important direction in the energy sector. Solar thermal power generation systems, as a clean energy technology, have broad application prospects. However, solar energy resources are intermittent and unstable, greatly affected by diurnal variations and weather conditions, leading to fluctuations in the output power of the power generation system and making it difficult to meet the stable operation requirements of the power grid. Furthermore, traditional solar thermal power generation systems still have room for improvement in energy conversion efficiency, especially in high-temperature heat collection and waste heat recovery, where there is potential for optimization.

[0003] In existing technologies, carbon dioxide systems are often designed with each cycle independently, lacking organic integration. This results in insufficient energy cascade utilization, inadequate energy storage and regulation capabilities, and an inability to achieve stable operation around the clock. Furthermore, the system's power generation capacity decreases significantly when sunlight is insufficient. Meanwhile, the design of energy storage systems is often limited in capacity or slow in response speed, making it difficult to smooth power output. To address this, we propose a supercritical carbon dioxide system that couples organic Rankine cycle waste heat utilization. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization.

[0005] This invention provides a supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization, comprising: A solar thermal collector module includes a solar collector, a first heater connected to the solar collector via a pipeline, and a second heater connected to the first heater via a pipeline, for using solar energy to heat molten salt in the solar thermal collector module pipeline and supplying heat to a carbon dioxide power cycle module through the heated molten salt; The carbon dioxide power cycle module includes a carbon dioxide turbine connected to the first heater pipeline and a heat exchanger connected to the carbon dioxide turbine pipeline, for receiving and utilizing the carbon dioxide working fluid heated by the first heater. The waste heat power generation module includes a high-temperature heat storage tank and a low-temperature heat storage tank connected to the heat exchanger piping, a working fluid evaporator connected to the high-temperature heat storage tank and the low-temperature heat storage tank piping, and a working fluid turbine connected to the working fluid evaporator piping, the working fluid turbine being connected to the second heater piping; and The energy storage heat exchange medium is disposed in the heat exchanger and circulates between the cold side of the heat exchanger, the high-temperature heat storage tank, the low-temperature heat storage tank and the working fluid evaporator during operation.

[0006] Furthermore, the carbon dioxide power cycle module also includes a carbon dioxide condenser connected to the heat exchanger pipeline and a carbon dioxide compressor connected to the carbon dioxide condenser pipeline, the carbon dioxide compressor being connected to the first heater pipeline.

[0007] Specifically, the working pressure range of the carbon dioxide working fluid inside the carbon dioxide turbine is 20-28 MPa, and the working temperature range of the carbon dioxide working fluid inside the carbon dioxide turbine is 500℃-550℃.

[0008] Specifically, the working pressure range of the carbon dioxide working medium inside the heat exchanger is 7-8 MPa, and the working temperature range of the carbon dioxide working medium inside the heat exchanger is 400-450℃.

[0009] Preferably, the cooling medium of the carbon dioxide condenser is water or air, the working temperature range of the carbon dioxide working medium in the carbon dioxide condenser is 30-40°C, and the working pressure range of the carbon dioxide working medium in the carbon dioxide condenser is 7-8 MPa.

[0010] Specifically, the working temperature range of the molten salt in the solar collector module pipeline is 500-600℃, and the molten salt is a mixture of nitrates.

[0011] Furthermore, the waste heat power generation module also includes a working fluid cooler connected to the working fluid turbine pipeline and a working fluid pump connected to the working fluid cooler pipeline.

[0012] Furthermore, the organic working fluid in the working turbine is R245fa or R123, the inlet pressure range of the organic working fluid in the working turbine is 1-2 MPa, and the inlet temperature range of the organic working fluid in the working turbine is 150-200°C.

[0013] Furthermore, the energy storage heat exchange medium is thermal storage oil, the operating temperature range of the thermal storage oil in the high-temperature thermal storage tank is 350-400℃, and the operating temperature range of the thermal storage oil in the low-temperature thermal storage tank is 30-50℃.

[0014] Specifically, the supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization further includes a monitoring and control module. The monitoring and control module includes sensor components installed in the solar collector module and the waste heat power generation module, a controller electrically connected to the sensor components, and a valve assembly electrically connected to the controller, for controlling the opening and closing of the valve assembly according to the signals from the sensor components. The sensor components include a light sensor installed on the solar collector and multiple temperature sensors installed on the pipeline of the waste heat power generation module. The valve assembly includes multiple electric valves installed on the pipeline of the carbon dioxide power cycle module and the waste heat power generation module.

[0015] The beneficial effects of this invention are as follows: This system is equipped with solar thermal collection modules, a carbon dioxide power cycle module, and a waste heat power generation module, organically integrating high-temperature solar thermal collection, supercritical carbon dioxide cycle, and organic Rankine cycle to achieve multi-stage energy utilization. The supercritical carbon dioxide cycle is highly efficient at high temperatures, while the organic Rankine cycle effectively recovers low-temperature waste heat, significantly improving the overall system's energy conversion efficiency. Through a heat transfer oil energy storage system, the system stores heat when sunlight is abundant and releases it when sunlight is insufficient or at night, ensuring stable power output and solving the intermittent nature of solar power generation, enabling all-weather utilization of renewable energy. The system uses valves for control, switching operating modes in real time based on sunlight and temperature signals, providing fast response and flexible operation. The energy storage system has a reasonable capacity design, supporting continuous operation of the system at rated power for 8-12 hours, enhancing the system's reliability and adaptability. Attached Figure Description

[0016] Figure 1 This is a structural connection diagram of a supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to a specific embodiment of the present invention.

[0017] Among them, 1 is a solar collector, 2 is a first heater, 3 is a second heater, 4 is a carbon dioxide compressor, 5 is a carbon dioxide condenser, 6 is a heat exchanger, 7 is a carbon dioxide turbine, 8 is a high-temperature heat storage tank, 9 is a low-temperature heat storage tank, 10 is a valve assembly, 11 is a working fluid evaporator, 12 is a working fluid pump, 13 is a working fluid cooler, and 14 is a working fluid turbine. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1 As shown in the figure, a supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization provided by a specific embodiment of the present invention includes: The solar thermal collector module includes a solar collector 1, a first heater 2 connected to the solar collector 1 via a pipeline, and a second heater 3 connected to the first heater 2 via a pipeline, for heating molten salt in the solar thermal collector module pipeline using solar energy and supplying heat to the carbon dioxide power circulation module through the heated molten salt; the carbon dioxide power circulation module includes a carbon dioxide turbine 7 connected to the first heater 2 via a pipeline and a heat exchanger 6 connected to the carbon dioxide turbine 7 via a pipeline, for receiving and utilizing the carbon dioxide working fluid heated by the first heater 2; the waste heat power generation module includes a high-temperature heat storage tank 8 and a low-temperature heat storage tank 9 connected to the heat exchanger 6 via a pipeline, a working fluid evaporator 11 connected to the high-temperature heat storage tank 8 and the low-temperature heat storage tank 9 via a pipeline, and a working fluid turbine 14 connected to the working fluid evaporator 11 via a pipeline, the working fluid turbine 14 being connected to the second heater 3 via a pipeline; and an energy storage heat exchange medium, disposed in the heat exchanger 6 and circulating between the cold side of the heat exchanger 6, the high-temperature heat storage tank 8, the low-temperature heat storage tank 9, and the working fluid evaporator 11 during operation.

[0020] Specifically, the working process of the solar thermal collector module is as follows: Solar collector 1 receives solar radiation and heats the molten salt in the collector circuit. After the molten salt is heated to about 500 to 600 degrees Celsius in the solar collector, it flows sequentially into the first heater 2 and the second heater 3. In the first heater 2, the molten salt transfers its heat to the carbon dioxide working fluid, raising the temperature of the carbon dioxide to the high temperature required for the turbine inlet. After releasing heat in the first heater 2, the temperature of the molten salt decreases, and it then enters the second heater 3. In the second heater 3, the molten salt continues to release heat to the organic working fluid or the heat storage working fluid, providing a medium-to-high temperature heat source for the subsequent waste heat power generation module. After two stages of heat release, the temperature of the molten salt decreases further, and it returns to the solar collector 1 to be reheated, forming a closed molten salt circuit. Through this process, solar heat is first used to drive the supercritical carbon dioxide main cycle, and then used for low-temperature power generation or energy storage, realizing the cascade utilization of solar energy.

[0021] Further, the working process of the carbon dioxide power cycle module is as follows: After being pressurized to a high pressure of about 20 to 28 MPa in the compressor, the carbon dioxide enters the first heater 2. In the first heater 2, it absorbs heat from the high-temperature molten salt, and the temperature rises to about 500 to 550 degrees Celsius. At this time, the carbon dioxide is in the supercritical high-temperature and high-pressure zone. The heated carbon dioxide enters the carbon dioxide turbine 7 and expands. In the turbine, it does work to drive the generator to generate electricity. The pressure and temperature decrease during the expansion process. The expanded high-temperature carbon dioxide enters the heat exchanger 6, where it transfers some of its heat to the heat storage medium on the cold side. Its own temperature drops to the range of 400 to 450 degrees Celsius, while still maintaining a high pressure of about 7 to 8 MPa. The carbon dioxide coming out of the heat exchanger 6 continues to enter the carbon dioxide condenser 5, where it exchanges heat with water or air and is further cooled to about 30 to 40 degrees Celsius, close to the critical temperature but still under high pressure. The cooled carbon dioxide then enters the compressor and is pressurized to a high pressure level of 20 to 28 MPa, returning to the first heater 2, completing the closed supercritical carbon dioxide cycle.

[0022] Furthermore, the working process of the waste heat power generation module is as follows: the heat storage medium from the cold side of heat exchanger 6 enters the high-temperature heat storage tank 8 for storage at a high temperature. When needed, it flows out from the high-temperature heat storage tank 8 to provide heat to the working medium evaporator 11, causing the organic working medium to evaporate. After releasing some heat, the temperature of the heat storage medium decreases, and it can return to the low-temperature heat storage tank 9 for low-temperature heat storage. In the working medium evaporator 11, the organic working medium absorbs heat from the heat storage medium or from the second heater 3, and is heated and evaporated from the liquid state into high-temperature and high-pressure steam. It enters the working medium turbine to expand and do work, generating electricity through the generator. The organic working medium discharged from the working medium turbine 14 enters the working medium cooler 13, where it is cooled and condensed by an external cooling medium. The condensed organic working medium is pressurized by the working medium pump and sent back to the working medium evaporator to form a closed organic Rankine cycle. Through the cooperation of the high-temperature heat storage tank 8 and the low-temperature heat storage tank 9, the waste heat power generation module can utilize the waste heat from the carbon dioxide cycle in real time, and can also store heat when solar energy is abundant and release heat when solar energy is insufficient, thereby smoothing the output power.

[0023] Based on the above basic implementation method, the carbon dioxide power cycle module also includes a carbon dioxide condenser 5 connected to the heat exchanger 6 via a pipeline and a carbon dioxide compressor 4 connected to the carbon dioxide condenser 5 via a pipeline. The carbon dioxide compressor 4 is connected to the first heater 2 via a pipeline.

[0024] Specifically, during the operation of the carbon dioxide power cycle module, heat exchanger 6 transfers the medium-to-high temperature waste heat of carbon dioxide to the heat storage medium, which not only reduces the load on the condenser but also provides a high-quality waste heat source for the subsequent modules.

[0025] In one specific embodiment, when the carbon dioxide turbine 7 is in operation, the pressure of the carbon dioxide working fluid inside the carbon dioxide turbine 7 ranges from 20 to 28 MPa, and the temperature of the carbon dioxide working fluid inside the carbon dioxide turbine 7 ranges from 500°C to 550°C; when the heat exchanger 6 is in operation, the pressure of the carbon dioxide working fluid inside the heat exchanger 6 ranges from 7 to 8 MPa, and the temperature of the carbon dioxide working fluid inside the heat exchanger 6 ranges from 400 to 450°C.

[0026] In this embodiment, the setting of the 7 parameters of the carbon dioxide turbine ensures that the carbon dioxide is in a supercritical high temperature and high pressure state. The critical pressure of carbon dioxide is approximately 7.38 MPa, and the critical temperature is approximately 31℃. Within the ranges of 20–28 MPa and above 500℃, the working fluid is far from the phase change region, resulting in stable property changes, which is conducive to stable turbine operation. Furthermore, it can achieve high cycle thermal efficiency. The high inlet pressure and temperature increase the turbine's expansion ratio and work capacity. Under the same heat exchange temperature conditions, more effective work can be extracted from the molten salt, thus significantly improving the power generation efficiency of the carbon dioxide cycle. Simultaneously, matching the temperature level with the solar molten salt (500℃–600℃ in the solar collector module) and setting the turbine inlet temperature to 500℃–550℃ fully utilizes the high-temperature potential of the molten salt while avoiding material strength and safety issues caused by excessively high temperatures. Sufficient medium-to-high-temperature waste heat can be reserved for subsequent waste heat utilization. Even when the turbine outlet enters heat exchanger 6 under high temperature and pressure conditions, it still maintains a relatively high temperature, ensuring that medium-to-high-grade heat is transferred to the heat storage working fluid, which is more beneficial to the efficiency of the subsequent organic Rankine cycle.

[0027] Furthermore, the pressure of the carbon dioxide working fluid in heat exchanger 6 is 7–8 MPa, and the temperature is 400–450 °C. Its main functions are: to ensure that the carbon dioxide remains in the supercritical or near-supercritical single-phase region within heat exchanger 6, avoiding significant phase changes during heat exchange, simplifying equipment design, and reducing flow and heat exchange instability; to ensure that the heat transferred to the heat storage medium has a sufficiently high grade. The temperature range of 400–450 °C can effectively heat the heat storage medium to above 300 °C, meeting both the subsequent heat storage temperature requirements and the evaporation temperature requirements of the organic Rankine cycle; to moderately reduce the temperature of the carbon dioxide, thus reducing the load on the condenser. After a significant portion of the heat has been released in heat exchanger 6, the temperature of the carbon dioxide entering the condenser is lower, reducing the heat that the condenser needs to discharge, thereby reducing the size of the cooling system or improving cooling efficiency; and to coordinate with the operating conditions of the condenser and compressor. The heat exchanger outlet pressure of 7–8 MPa, consistent with the pressure range set in the condenser, ensures stable pressure changes, which is beneficial to the design and operation of the condenser and compressor.

[0028] In another specific embodiment, the cooling medium of the carbon dioxide condenser 5 is water or air. When the carbon dioxide condenser 5 is working, the temperature range of the carbon dioxide working medium inside the carbon dioxide condenser 5 is 30 to 40°C, and the pressure range of the carbon dioxide working medium inside the carbon dioxide condenser 5 is 7 to 8 MPa.

[0029] Specifically, the parameters set within the condenser serve several purposes: First, they facilitate engineering implementation by selecting common cold sources. Water cooling and air cooling are the most prevalent cooling methods in industry, adaptable to different regional water resources and environmental conditions, making the system more flexible in scale-up and layout. Second, they cool carbon dioxide to near its critical point while maintaining high pressure, bringing it close to a supercritical state. At 30–40℃ and 7–8 MPa, the working fluid density is relatively high, resulting in lower compression work requirements, which helps reduce compressor energy consumption and improve overall cycle efficiency. Third, they control the heat exchange temperature difference within a reasonable range. With ambient temperatures typically between 10 and 30 degrees Celsius, controlling the condenser outlet carbon dioxide temperature between 30 and 40℃ ensures sufficient heat transfer driving force without requiring excessively large heat exchange areas and cooling work due to excessively low temperatures. Fourth, they ensure close matching with upstream and downstream equipment. The condenser outlet pressure matches the internal pressure of heat exchanger 6, creating a stable high-pressure loop from heat exchanger 6 to the condenser and then to the compressor, eliminating the need for significant throttling or diffusion after condensation, thus simplifying the system.

[0030] In one specific embodiment, the molten salt temperature range in the pipeline of the solar thermal collector module is 500-600°C, and the molten salt is a mixture of nitrates; the waste heat power generation module also includes a working fluid cooler 13 connected to the working fluid turbine pipeline and a working fluid pump 12 connected to the working fluid cooler 13 pipeline; the organic working fluid in the working fluid turbine 14 is R245fa or R123, the inlet pressure range of the organic working fluid in the working fluid turbine 14 is 1-2 MPa, and the inlet temperature range of the organic working fluid in the working fluid turbine 14 is 150-200°C.

[0031] In this embodiment, the organic working fluid used is R245fa or R123. Both types of working fluids possess thermophysical properties suitable for medium- and low-temperature organic Rankine cycles, with the following advantages: low boiling point and moderate saturated vapor pressure. At an evaporation temperature of 150–200°C, a suitable vapor pressure of approximately one to two MPa can be obtained. This pressure range facilitates the design and manufacture of turbines and pipelines, eliminating the need to withstand extreme high pressures. They also exhibit good thermal stability. Within the commonly used temperature range of organic Rankine cycles, they possess good chemical stability, are not easily decomposed, and are beneficial for extending the service life of the working fluid and equipment. Furthermore, they are well-matched to the temperature of the thermal storage oil. With the thermal storage oil temperature ranging from 300 to 400 degrees Celsius and the organic working fluid evaporation temperature controlled between 150 and 200 degrees Celsius, high heat exchange efficiency can be achieved through reasonable heat exchange area and temperature difference design. This fully utilizes the heat of the thermal storage oil while preventing overheating and decomposition of the organic working fluid.

[0032] Specifically, the inlet pressure of the working fluid turbine 14 is 1–2 MPa, and the inlet temperature is 150–200 °C. The parameters serve several purposes: achieving a suitable expansion ratio and turbine work output. Within this pressure and temperature range, the organic working fluid vapor has a sufficiently high specific enthalpy, allowing the turbine expansion to output considerable mechanical work without causing excessively low turbine outlet pressure, which could lead to condensation or a significant decrease in efficiency; ensuring complete vaporization of the organic working fluid at the turbine inlet with a certain degree of superheat. By controlling the inlet temperature between 150 and 200 °C, it is ensured that the working fluid will not liquefy within the passage during turbine operation, preventing erosion and vibration of the blades and improving equipment reliability; in coordination with equipment materials and safety requirements, the 1–2 MPa operating pressure is significantly lower than that of high-pressure steam systems, allowing the use of lower-cost, less demanding equipment materials and sealing structures, reducing system cost and safety risks; and synergizing with the temperature gradient of the thermal storage system. The thermal oil has a high temperature of 300 to 400 degrees Celsius and a low temperature of 30 to 50 degrees Celsius. The evaporation temperature and pressure of the organic working fluid are set in the middle range, which is conducive to maintaining a reasonable average temperature difference in a heat exchange process with a large temperature gradient and improving the efficiency of the second method of the organic Rankine cycle.

[0033] In another specific embodiment, the energy storage heat exchange medium is thermal storage oil. When the high-temperature thermal storage tank 8 is working, the temperature range of the thermal storage oil in the high-temperature thermal storage tank 8 is 350-400°C, and when the low-temperature thermal storage tank 9 is working, the temperature range of the thermal storage oil in the low-temperature thermal storage tank 9 is 30-50°C. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization also includes a monitoring and control module. The monitoring and control module includes sensor components installed in the solar collector module and the waste heat power generation module, a controller electrically connected to the sensor components, and a valve assembly electrically connected to the controller, for controlling the opening and closing of the valve assembly according to the signals from the sensor components. The sensor components include a light sensor installed on the solar collector 1 and multiple temperature sensors installed on the pipeline of the waste heat power generation module. The valve assembly includes multiple electric valves installed on the pipeline of the carbon dioxide power cycle module and the waste heat power generation module.

[0034] Furthermore, the thermal storage tank capacity is designed to allow the system to operate continuously for 8-12 hours at rated power. The valve assembly includes a first valve group installed on the pipelines between heat exchanger 6 and high-temperature thermal storage tank 8, and between heat exchanger 6 and low-temperature thermal storage tank 9; a second valve group installed on the pipelines between working fluid evaporator 11 and high-temperature thermal storage tank 8, and between working fluid evaporator 11 and low-temperature thermal storage tank 9; a flow valve on the pipeline between working fluid pump 12 and working fluid evaporator 11; and a control valve on the pipeline between working fluid evaporator 11 and second heater 3. When there is sufficient sunlight: the first valve group is opened and the second valve group is closed. At this time, the solar molten salt system operates first, and the molten salt transfers heat through the first heater 2 and the second heater 3. The supercritical carbon dioxide system generates electricity normally. The organic Rankine cycle relies solely on the second heater 3 to heat the organic working fluid, achieving waste heat recovery for power generation. The energy storage system is connected to heat exchanger 6 through the first valve group to store excess heat or supplement heat. When there is insufficient sunlight or at night: the second valve group is opened and the first valve group is closed. At this time, solar thermal collection weakens, the energy storage system releases heat, and high-temperature heat transfer oil enters the working fluid evaporator 11 through a valve in the second valve group to heat the organic working fluid and drive the organic Rankine cycle to generate electricity. Simultaneously, the supercritical carbon dioxide system may reduce its load or rely on energy storage to maintain operation. This mode ensures continuous power generation even under conditions of no sunlight, and the organic Rankine cycle generates electricity using a low-temperature heat source, improving the overall system efficiency.

[0035] Furthermore, the sensor assembly includes a light sensor on the solar collector 1 and multiple temperature sensors on the waste heat power generation module pipeline. Its main function is to monitor the system's operating status in real time and provide data for the controller. The light sensor measures the current solar irradiance and its changing trend. The controller determines whether the solar input is sufficient based on the light intensity, thus deciding whether to prioritize heat storage, maintain the current power generation load, or reduce power output. Temperature sensors are located at key locations such as the molten salt pipeline, the heat storage medium pipeline, and the organic working medium pipeline to monitor the temperature of the working medium in real time. The controller uses this temperature information to determine whether the molten salt has reached the set heat collection temperature, whether the heat storage oil has met the requirements for heat storage or release, and whether the organic working medium is operating within a safe and stable temperature range, thereby adjusting valve opening, pump start / stop, and load distribution. Through the sensor assembly, automated system monitoring, anomaly warnings, and safety interlocks can be achieved. For example, when the temperature is too high, relevant valves can be closed or heating can be stopped to prevent equipment damage due to overheating.

[0036] To aid in a better understanding of the invention, a more comprehensive and specific embodiment is described, in which the invention provides a supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization, comprising: The solar thermal collector module includes a solar collector 1, a first heater 2 connected to the solar collector 1 via a pipeline, and a second heater 3 connected to the first heater 2 via a pipeline, for heating molten salt in the solar thermal collector module pipeline using solar energy and supplying heat to the carbon dioxide power circulation module through the heated molten salt; the carbon dioxide power circulation module includes a carbon dioxide turbine 7 connected to the first heater 2 via a pipeline and a heat exchanger 6 connected to the carbon dioxide turbine 7 via a pipeline, for receiving and utilizing the carbon dioxide working fluid heated by the first heater 2; the waste heat power generation module includes a high-temperature heat storage tank 8 and a low-temperature heat storage tank 9 connected to the heat exchanger 6 via a pipeline, a working fluid evaporator 11 connected to the high-temperature heat storage tank 8 and the low-temperature heat storage tank 9 via a pipeline, and a working fluid turbine 14 connected to the working fluid evaporator 11 via a pipeline, the working fluid turbine 14 being connected to the second heater 3 via a pipeline; and an energy storage heat exchange medium, disposed in the heat exchanger 6 and circulating between the cold side of the heat exchanger 6, the high-temperature heat storage tank 8, the low-temperature heat storage tank 9, and the working fluid evaporator 11 during operation.

[0037] In this embodiment, the carbon dioxide power cycle module further includes a carbon dioxide condenser 5 connected to the heat exchanger 6 via piping and a carbon dioxide compressor 4 connected to the carbon dioxide condenser 5 via piping. The carbon dioxide compressor 4 is connected to the first heater 2 via piping. When the carbon dioxide turbine 7 is working, the pressure range of the carbon dioxide working fluid inside the carbon dioxide turbine 7 is 20–28 MPa, and the temperature range of the carbon dioxide working fluid inside the carbon dioxide turbine 7 is 500°C–550°C. When the heat exchanger 6 is working, the pressure range of the carbon dioxide working fluid inside the heat exchanger 6 is 7–8 MPa, and the temperature range of the carbon dioxide working fluid inside the heat exchanger 6 is 400–450°C. The cooling medium of the carbon dioxide condenser 5 is water or air, and the temperature range of the carbon dioxide working fluid inside the carbon dioxide condenser 5 is 30–40°C. During operation, the working fluid pressure inside the carbon dioxide condenser 5 ranges from 7 to 8 MPa; the molten salt temperature in the pipeline of the solar collector module ranges from 500 to 600°C, and the molten salt is a mixture of nitrates; the waste heat power generation module also includes a working fluid cooler 13 connected to the working fluid turbine 14 and a working fluid pump 12 connected to the working fluid cooler 13; the organic working fluid in the working fluid turbine 14 during operation is R245fa or R123. When the working medium turbine 14 is in operation, the inlet pressure of the organic working medium in the working medium turbine 14 is in the range of 1 to 2 MPa, and the inlet temperature of the organic working medium in the working medium turbine 14 is in the range of 150 to 200°C. The energy storage heat exchange medium is thermal oil. When the high-temperature thermal storage tank 8 is in operation, the temperature of the thermal oil in the high-temperature thermal storage tank 8 is in the range of 350 to 400°C, and when the low-temperature thermal storage tank 9 is in operation, the temperature of the thermal oil in the low-temperature thermal storage tank 9 is in the range of 30 to 50°C.

[0038] Specifically, the supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization also includes a monitoring and control module. The monitoring and control module includes sensor components installed in the solar collector module and the waste heat power generation module, a controller electrically connected to the sensor components, and a valve assembly electrically connected to the controller, for controlling the opening and closing of the valve assembly according to the signals from the sensor components. The sensor components include a light sensor installed on the solar collector 1 and multiple temperature sensors installed on the pipeline of the waste heat power generation module. The valve assembly includes multiple electric valves installed on the pipeline of the carbon dioxide power cycle module and the waste heat power generation module.

[0039] In summary, the embodiments disclosed herein have at least the following technical effects: By setting up a solar thermal collector module, a carbon dioxide power cycle module, and a waste heat power generation module, the solar thermal collector module heats the molten salt to 500℃~550℃. First, it serves as a high-temperature heat source to drive the supercritical carbon dioxide power cycle for power generation. After the carbon dioxide turbine expands, the working fluid further releases heat to the heat storage working fluid in the heat exchanger 6. Then, the heat storage working fluid drives the organic Rankine cycle for secondary power generation, forming a cascade utilization path, which significantly improves the overall energy utilization rate and power generation efficiency of the system. The inlet pressure of the carbon dioxide turbine 7 is limited to 20-28 MPa and the inlet temperature to 500-550℃, while the carbon dioxide pressure inside the heat exchanger is limited to 7-8 MPa and the temperature to 400-450℃. This ensures that the carbon dioxide is in the supercritical or near-supercritical single-phase region in both the turbine and the heat exchanger 6. On the one hand, this improves the turbine's expansion work capacity and cycle thermal efficiency; on the other hand, it ensures a stable and reliable heat exchange process, facilitating the efficient transfer of medium- to high-grade waste heat to the heat storage medium, and providing a high-quality heat source for subsequent energy storage and organic Rankine cycles. The carbon dioxide temperature in the carbon dioxide condenser 5 is limited to 30-40 degrees Celsius and the pressure is limited to 7-8 MPa, with water or air selected as the cooling medium. By cooling the carbon dioxide to a high-pressure state close to its critical temperature, the specific power consumption of the compressor is reduced, and the energy loss during the compression process is decreased. On the other hand, the heat exchange load of the condenser is reduced while ensuring the heat exchange driving force, making the cooling system structure more compact and further reducing the overall energy consumption of the system. Thermal oil is used as the working fluid for heat storage, and the temperatures of the high-temperature thermal storage tank 8 and the low-temperature thermal storage tank 9 are limited to the ranges of 350–400℃ and 30–50℃, respectively, to achieve a reasonable classification of high-temperature heat storage and low-temperature heat recovery. The thermal oil circulating between the cold side of the heat exchanger 6 and the working fluid evaporator 11 concentrates the waste heat discharged from the carbon dioxide circulation in the high-temperature thermal storage tank 8, and releases it as needed in the working fluid evaporator 11. Simultaneously, the released low-temperature thermal oil is recovered to the low-temperature thermal storage tank 9, achieving dual regulation of heat in both time and temperature, which is beneficial for improving energy storage density and waste heat utilization rate. R245fa or R123 was selected as the organic working fluid, and the inlet pressure of the working fluid turbine 14 was limited to 1-2 MPa and the inlet temperature to 150-200℃. This ensured a good match between the operating conditions of the organic Rankine cycle and the high temperature range of 350-400℃ and the low temperature range of 30-50℃ of the thermal storage oil. This guaranteed that the working fluid had appropriate superheat and specific enthalpy at the turbine inlet, resulting in higher turbine output power; and that the system pressure level remained moderate, facilitating equipment selection and safety control. Through the optimized configuration of the working fluid type and parameters, the efficiency and operational reliability of the medium- and low-temperature waste heat power generation process were significantly improved. By organically coupling the solar thermal collector module, the carbon dioxide power cycle module, and the waste heat power generation module, this invention can generate electricity at high loads directly using molten salt and the main carbon dioxide cycle when solar energy is abundant, and simultaneously store heat in the thermal storage tank; it can also maintain continuous power generation of the organic Rankine cycle by releasing heat from the high-temperature thermal storage tank 8 when solar irradiance is reduced or during nighttime operation, thereby achieving smooth output of power generation over time and enhancing the system's adaptability to solar energy fluctuations and grid friendliness. The monitoring and control module incorporates a light irradiance sensor and multiple temperature sensors, forming a valve assembly with electric valves to create a closed-loop control system with the controller. The light irradiance sensor monitors solar irradiance in real time, while the temperature sensors monitor the temperatures of key components such as molten salt, thermal storage oil, and the organic working fluid. The controller automatically adjusts the opening degree of the electric valves and the flow path combination based on the sensor signals, enabling automatic switching of heat distribution and operating modes between the carbon dioxide power cycle, thermal storage unit, and organic Rankine cycle under different solar energy conditions and load demands. This ensures stable and efficient system operation under complex conditions, improves operational safety and automation, and reduces the need for manual intervention.

[0040] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization, characterized in that, include: A solar thermal collector module includes a solar collector, a first heater connected to the solar collector via a pipeline, and a second heater connected to the first heater via a pipeline, for using solar energy to heat molten salt in the solar thermal collector module pipeline and supplying heat to a carbon dioxide power cycle module through the heated molten salt; The carbon dioxide power cycle module includes a carbon dioxide turbine connected to the first heater pipeline and a heat exchanger connected to the carbon dioxide turbine pipeline, for receiving and utilizing the carbon dioxide working fluid heated by the first heater. The waste heat power generation module includes a high-temperature heat storage tank and a low-temperature heat storage tank connected to the heat exchanger pipeline, a working fluid evaporator connected to the high-temperature heat storage tank and the low-temperature heat storage tank pipeline, and a working fluid turbine connected to the working fluid evaporator pipeline, wherein the working fluid turbine is connected to the second heater pipeline. as well as The energy storage heat exchange medium is disposed in the heat exchanger and circulates between the cold side of the heat exchanger, the high-temperature heat storage tank, the low-temperature heat storage tank and the working fluid evaporator during operation.

2. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to claim 1, characterized in that, The carbon dioxide power cycle module also includes a carbon dioxide condenser connected to the heat exchanger pipeline and a carbon dioxide compressor connected to the carbon dioxide condenser pipeline, wherein the carbon dioxide compressor is connected to the first heater pipeline.

3. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to claim 2, characterized in that, The working pressure range of the carbon dioxide working medium inside the carbon dioxide turbine is 20-28 MPa, and the working temperature range of the carbon dioxide working medium inside the carbon dioxide turbine is 500℃-550℃.

4. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to claim 3, characterized in that, The working pressure range of the carbon dioxide working medium inside the heat exchanger is 7-8 MPa, and the working temperature range of the carbon dioxide working medium inside the heat exchanger is 400-450℃.

5. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to claim 3, characterized in that, The cooling medium of the carbon dioxide condenser is water or air, the working temperature range of the carbon dioxide working medium in the carbon dioxide condenser is 30-40°C, and the working pressure range of the carbon dioxide working medium in the carbon dioxide condenser is 7-8 MPa.

6. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to claim 1, characterized in that, The working temperature range of the molten salt in the pipeline of the solar collector module is 500-600℃, and the molten salt is a mixture of nitrates.

7. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to claim 1, characterized in that, The waste heat power generation module also includes a working fluid cooler connected to the working fluid turbine pipeline and a working fluid pump connected to the working fluid cooler pipeline.

8. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to claim 7, characterized in that, The organic working fluid in the working turbine is R245fa or R123, the inlet pressure range of the organic working fluid in the working turbine is 1-2 MPa, and the inlet temperature range of the organic working fluid in the working turbine is 150-200°C.

9. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to claim 1, characterized in that, The energy storage heat exchange medium is thermal oil. The working temperature range of the thermal oil in the high-temperature thermal storage tank is 350-400℃, and the working temperature range of the thermal oil in the low-temperature thermal storage tank is 30-50℃.

10. The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization according to any one of claims 1 to 9, characterized in that, The supercritical carbon dioxide system coupled with organic Rankine cycle waste heat utilization also includes a monitoring and control module. The monitoring and control module includes sensor components installed in the solar collector module and the waste heat power generation module, a controller electrically connected to the sensor components, and a valve assembly electrically connected to the controller, for controlling the opening and closing of the valve assembly according to the signals from the sensor components. The sensor components include a light sensor installed on the solar collector and multiple temperature sensors installed on the pipeline of the waste heat power generation module. The valve assembly includes multiple electric valves installed on the pipeline of the carbon dioxide power cycle module and the waste heat power generation module.

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