Supercritical carbon dioxide high-efficiency thermodynamic cycle system

Abstract

The embodiment of the present disclosure provides a supercritical carbon dioxide high-efficiency thermodynamic cycle system, comprising: a compression unit for performing a staged compression process on air, the compression unit being provided with an air inlet and an air outlet; a top cycle unit connected with the air outlet of the compression unit, for preheating, combustion and high-temperature energy conversion power generation on an air working medium, the top cycle unit being provided with a high-temperature exhaust outlet; and a bottom cycle unit connected with the high-temperature exhaust outlet of the top cycle unit, for receiving high-temperature exhaust waste heat of the top cycle unit through heat exchange to heat carbon dioxide working medium to form a thermodynamic cycle inside the carbon dioxide working medium; wherein the compression unit, the top cycle unit and the bottom cycle unit constitute a double-cycle heat gradient utilization architecture.

Description

Technical Field

[0001] The embodiments disclosed herein belong to the field of thermal engineering technology, specifically relating to a supercritical carbon dioxide high-efficiency thermal cycle system. Background Technology

[0002] In the current energy sector, traditional thermodynamic cycle systems, such as the simple Brayton and Rankine cycles, have many limitations in energy utilization. These systems often fail to fully utilize the heat generated by fuel combustion, resulting in a significant loss of thermal energy as waste gases and other forms of energy waste.

[0003] In traditional thermal cycles, the waste heat of high-temperature gases is not fully recovered and reused, resulting in a significant amount of heat being directly released into the environment and causing substantial energy waste. Traditional cycle systems also fail to effectively utilize energy according to its quality, leading to a mixture of high-grade and low-grade energy and hindering optimal energy utilization. With the continued growth of global energy demand and increasingly stringent environmental requirements, the development of more efficient and energy-saving thermal cycle systems is urgently needed. While some existing improved thermal cycle systems have optimized traditional systems to some extent, there is still considerable room for improvement in terms of cycle integration, the efficiency of heat exchange equipment, and overall performance optimization, making it difficult to meet the current dual demands for efficient energy utilization and environmental protection.

[0004] Therefore, this invention aims to provide a gas turbine supercritical carbon dioxide high-efficiency thermodynamic cycle system, which uses air as the top circulation medium and carbon dioxide as the bottom circulation medium to solve the above problems. Summary of the Invention

[0005] The embodiments disclosed herein are intended to at least address one of the technical problems existing in the prior art, and to provide a supercritical carbon dioxide high-efficiency thermodynamic cycle system.

[0006] One aspect of the embodiments of this disclosure provides a supercritical carbon dioxide high-efficiency thermodynamic cycle system, comprising: A compression unit is used for staged compression of air, and the compression unit is provided with an air inlet and an air outlet; The top circulation unit is connected to the air outlet of the compression unit and is used to preheat, combust, and convert air working fluid into high-temperature energy for power generation. The top circulation unit is equipped with a high-temperature exhaust outlet. The bottom circulation unit is connected to the high-temperature exhaust outlet of the top circulation unit and is used to receive the waste heat of the high-temperature exhaust from the top circulation unit through heat exchange to heat the carbon dioxide working fluid to form a thermodynamic cycle inside it. The compression unit, the top circulation unit, and the bottom circulation unit constitute a dual-cycle heat cascade utilization architecture.

[0007] Optionally, the compression unit includes a first compressor, an intercooler, and a second compressor connected in sequence, wherein the first compressor is provided with the air inlet and the second compressor is provided with the air outlet.

[0008] Optionally, the top circulation unit includes a top circulation regenerator connected to the air outlet with a cold side inlet, a combustion chamber connected to the cold side outlet of the top circulation regenerator with an inlet, and a first turbine connected to the outlet of the combustion chamber with an inlet, the first turbine being provided with a high-temperature exhaust outlet.

[0009] Optionally, the bottom circulation unit includes a first bottom circulation heater whose hot-side inlet is connected to the high-temperature exhaust outlet of the first turbine, a second turbine whose inlet is connected to the cold-side outlet of the first bottom circulation heater, a first regenerator, a second regenerator and a cooler connected in sequence to the outlet of the second turbine, a third compressor whose inlet is connected to the outlet of the cooler and whose outlet is connected to the cold-side inlet of the second regenerator, and a second bottom circulation heater. The hot-side inlet of the second bottom circulation heater is connected to the hot-side outlet of the top circulation regenerator, the cold-side outlet of the second bottom circulation heater is connected to the cold-side inlet of the first regenerator, and the cold-side inlet of the second bottom circulation heater is connected to the cold-side outlet of the second regenerator.

[0010] Furthermore, it also includes: a first generator, which is connected to the first turbine drive.

[0011] Furthermore, it also includes a second generator, which is connected to the second turbine drive.

[0012] Optionally, the intercooler includes a plate heat exchanger.

[0013] The beneficial effects of the embodiments of this disclosure include: In this application, a three-stage collaborative architecture consisting of a compression unit, a top-cycle unit, and a bottom-cycle unit is used to achieve cascaded utilization of heat from both air and carbon dioxide as working fluids. The top-cycle unit directly generates electricity using high-temperature combustion energy, while the bottom-cycle unit efficiently recovers waste heat from medium- and low-temperature exhaust gas for secondary power generation. Combined with a multi-stage regenerative design, this significantly improves the system's thermal efficiency while reducing fuel consumption and pollutant emissions, thus offering both high efficiency, energy saving, and environmental protection advantages. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a supercritical carbon dioxide high-efficiency thermodynamic cycle system according to an embodiment of the present disclosure.

[0015] In the diagram, 1 is the first compressor; 2 is the intercooler; 3 is the second compressor; 4 is the top cycle regenerator; 5 is the combustion chamber; 6 is the first turbine; 7 is the first bottom cycle heater; 8 is the second turbine; 9 is the first regenerator; 10 is the second regenerator; 11 is the cooler; 12 is the second bottom cycle heater; 13 is the first generator; 14 is the second generator; and 15 is the third compressor. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions of this disclosure, the disclosure will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] The embodiments of this application will be further described in detail below with reference to the accompanying drawings and examples. The detailed descriptions and accompanying drawings of the following embodiments are used to exemplarily illustrate the principles of this application, but should not be used to limit the scope of this application; that is, this application is not limited to the described embodiments. In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0018] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application depending on the specific circumstances.

[0019] like Figure 1 As shown, a supercritical carbon dioxide high-efficiency thermodynamic cycle system includes: A compression unit is used to perform staged compression of air, and the compression unit is provided with an air inlet and an air outlet.

[0020] The top circulation unit is connected to the air outlet of the compression unit and is used to preheat, combust, and convert air working fluid into high-temperature energy for power generation. The top circulation unit is equipped with a high-temperature exhaust outlet.

[0021] The bottom circulation unit is connected to the high-temperature exhaust outlet of the top circulation unit and is used to receive the waste heat of the high-temperature exhaust from the top circulation unit through heat exchange to heat the carbon dioxide working fluid to form a thermodynamic cycle inside it.

[0022] The compression unit, the top circulation unit, and the bottom circulation unit constitute a dual-cycle heat cascade utilization architecture.

[0023] In this application, a three-stage collaborative architecture consisting of a compression unit, a top-cycle unit, and a bottom-cycle unit is used to achieve cascaded utilization of heat from both air and carbon dioxide as working fluids. The top-cycle unit directly generates electricity using high-temperature combustion energy, while the bottom-cycle unit efficiently recovers waste heat from medium- and low-temperature exhaust gas for secondary power generation. Combined with a multi-stage regenerative design, this significantly improves the system's thermal efficiency while reducing fuel consumption and pollutant emissions, thus offering both high efficiency, energy saving, and environmental protection advantages.

[0024] In some embodiments, the compression unit includes a first compressor 1, an intercooler 2, and a second compressor 3 connected in sequence, wherein the first compressor 1 is provided with the air inlet and the second compressor 3 is provided with the air outlet.

[0025] In this application, the staged compression design of the first compressor 1, the intercooler 2 and the second compressor 3, combined with the intermediate cooling treatment, can significantly reduce compression energy consumption and equipment thermal stress, and improve the overall energy efficiency and operational stability of the system.

[0026] In some embodiments, the top circulation unit includes a top circulation regenerator 4 with a cold-side inlet connected to the air outlet, a combustion chamber 5 with an inlet connected to the cold-side outlet of the top circulation regenerator 4, and a first turbine 6 with an inlet connected to the outlet of the combustion chamber 5, the first turbine 6 being provided with a high-temperature exhaust outlet.

[0027] In this application, the series design of the top circulation regenerator 4, combustion chamber 5 and first turbine 6 realizes compressed air preheating, high-temperature combustion and energy cascade conversion, which greatly improves combustion efficiency and power generation efficiency.

[0028] In some embodiments, the bottom circulation unit includes a first bottom circulation heater 7 whose hot-side inlet is connected to the high-temperature exhaust outlet of the first turbine 6, a second turbine 8 whose inlet is connected to the cold-side outlet of the first bottom circulation heater 7, a first regenerator 9, a second regenerator 10 and a cooler 11 connected in sequence to the outlet of the second turbine 8, a third compressor 15 whose inlet is connected to the outlet of the cooler 11 and whose outlet is connected to the cold-side inlet of the second regenerator 10, and a second bottom circulation heater 12.

[0029] The hot-side inlet of the second bottom circulation heater 12 is connected to the hot-side outlet of the top circulation regenerator 4, the cold-side outlet of the second bottom circulation heater 12 is connected to the cold-side inlet of the first regenerator 9, and the cold-side inlet of the second bottom circulation heater 12 is connected to the cold-side outlet of the second regenerator 10.

[0030] In this application, a complete heat recovery chain is constructed through the multi-stage coordinated layout of the first bottom circulation heater 7, the second bottom circulation heater 12 and the two-stage regenerator: the first bottom circulation heater 7 recovers the waste heat of the high-temperature exhaust gas of the first turbine 6, and the second bottom circulation heater 12 further utilizes the medium-temperature waste heat at the outlet of the top circulation regenerator 4, and cooperates with the regenerator to preheat the working fluid in multiple stages. This setup can significantly improve the utilization efficiency of low-temperature heat and maximize the overall energy efficiency of the system.

[0031] In some embodiments, it further includes a first generator 13, which is drive-connected to the first turbine 6.

[0032] In some embodiments, it further includes a second generator 14, which is drive-connected to the second turbine 8.

[0033] In some embodiments, the intercooler 2 includes a plate heat exchanger.

[0034] Specifically, the compression unit consists of a first compressor 1, an intercooler 2, and a second compressor 3 connected in sequence, used for staged compression and intercooling of air.

[0035] The top-circulation unit includes a top-circulation regenerator 4 connected to the outlet of the second compressor 3, a combustion chamber 5 connected to the outlet of the top-circulation regenerator 4, and a first turbine 6 connected to the outlet of the combustion chamber 5. The top-circulation unit is used to preheat air, combust it, and convert energy into electricity. The first turbine 6 is provided with a high-temperature exhaust outlet.

[0036] The bottom circulation unit includes a first bottom circulation heater 7 connected to the high-temperature exhaust outlet of the first turbine 6, a second turbine 8 connected to the outlet of the first bottom circulation heater 7, a first regenerator 9, a second regenerator 10, and a cooler 11 sequentially connected to the outlet of the second turbine 8, a third compressor 15 connected to the outlet of the cooler 11, and a connection structure for the pipeline connecting the outlet of the third compressor 15 to the second regenerator 10 and the second bottom circulation heater 12, which is used to realize the heating, work, waste heat recovery, cooling and compression cycle of the bottom circulation working fluid carbon dioxide.

[0037] A heat exchange channel is provided between the top circulation regenerator 4 and the first bottom circulation heater 7 to achieve heat transfer.

[0038] The first compressor 1 is used to initially compress the air entering the system, increase the air pressure, and prepare for the subsequent compression process. The intercooler 2 is used to reduce the temperature of the air after compression by the first compressor 1, and reduce the energy consumption and thermal stress of the equipment during the compression process of the second compressor 3.

[0039] The second compressor 3 is used to perform secondary compression on the air cooled by the intercooler 2, so that the air reaches the pressure required for the top cycle.

[0040] The top circulation regenerator 4 is used to recover the waste heat of the gas in the top circulation and preheat the air entering the combustion chamber 5 to improve combustion efficiency.

[0041] The combustion chamber 5 is used to fully mix and burn preheated air and fuel to produce high-temperature and high-pressure gas, which provides an energy source for the first turbine 6 to do work.

[0042] The first turbine 6 is used to convert the internal energy of the high-temperature and high-pressure gas generated in the combustion chamber 5 into mechanical energy to drive the first generator 13 to generate electricity.

[0043] The first bottom circulation heater 7 is used to absorb the residual heat of the gas after the top circulation turbine has done its work, and to heat the bottom circulation working medium carbon dioxide.

[0044] The second turbine 8 is used to convert the internal energy of the heated bottom circulating working fluid into mechanical energy, which drives the second generator 14 to generate electricity.

[0045] The first regenerator 9 and the second regenerator 10 are used to recover the waste heat after the bottom circulation working fluid has done work, thereby further improving the energy utilization efficiency of the system.

[0046] The cooler 11 is used to cool the bottom circulation working fluid carbon dioxide to a suitable temperature to meet the intake requirements of the third compressor 15. The third compressor 15 is used to compress and increase the pressure of the cooled bottom circulation working fluid carbon dioxide, so that it re-enters the bottom circulation process.

[0047] This application achieves tiered utilization of heat through a dual-cycle architecture and multi-stage regeneration design, thereby significantly improving energy conversion efficiency.

[0048] This invention provides a high-efficiency supercritical carbon dioxide thermodynamic cycle system for gas turbines, which solves the problem of low overall efficiency in waste heat recovery in existing technologies. Specifically: The compression unit includes a first compressor 1, an intercooler 2, and a second compressor 3. The first compressor 1 is used to initially compress the air entering the system, increasing the air pressure. The intercooler 2 cools the initially compressed air, reducing its temperature and decreasing energy consumption in subsequent compression processes. The second compressor 3 further compresses the cooled air to the pressure required to enter the top-cycle regenerator 4.

[0049] The top-cycle unit consists of a top-cycle regenerator 4, a combustion chamber 5, and a first turbine 6. The top-cycle regenerator 4 recovers heat from the air in the top cycle and preheats the air about to enter the combustion chamber 5. In the combustion chamber 5, the preheated air mixes thoroughly with the fuel and burns, producing high-temperature, high-pressure gas. The first turbine 6 uses the energy of the high-temperature, high-pressure gas to do work, driving the first generator 13(G) to generate electricity.

[0050] The bottom circulation unit includes a first bottom circulation heater 7, a second turbine 8, a first regenerator 9, a second bottom circulation heater 12, a second regenerator 10, a cooler 11, and a third compressor 15. The first bottom circulation heater 7 receives heat from the air after the first turbine 6 has performed work, heating the carbon dioxide working fluid in the bottom circulation. The second turbine 8 uses the energy of the heated carbon dioxide working fluid to perform work, driving the second engine to generate electricity. The first regenerator 9 and the second regenerator 10 respectively recover the waste heat of the bottom circulation carbon dioxide working fluid after it has performed work, further improving the system's thermal efficiency. The cooler 11 cools the bottom circulation carbon dioxide working fluid to a suitable temperature, facilitating compression by the third compressor 15 and allowing it to re-enter the circulation.

[0051] The above structures are interconnected by pipes to form a whole thermal circulation system, and realize a highly efficient architecture for top and bottom dual circulation to work together.

[0052] In this process, air first enters through the first compressor 1. Inside the first compressor 1, the air is compressed in volume and its pressure increases under the action of mechanical force. This process follows the basic principle of gas compression, increasing the pressure energy of the gas by consuming mechanical energy. The temperature of the compressed air also increases accordingly. To reduce energy consumption in subsequent compression processes and ensure the safe operation of the equipment, the air flows into the intercooler 2 for cooling.

[0053] In the intercooler 2, air exchanges heat with a cooling medium (such as cooling water or cold air), thus lowering its own temperature. The cooled air then enters the second compressor 3 for further compression, increasing its pressure to meet the needs of subsequent stages in the top cycle.

[0054] After being compressed twice, the air enters the top-cycle regenerator 4. In the top-cycle regenerator 4, the air exchanges heat with the high-temperature air from the top-cycle regenerator 4, absorbing heat and raising its temperature. This process utilizes the principle of heat transfer from a high-temperature object to a low-temperature object, achieving energy recovery and reuse. The preheated air then enters the combustion chamber 5, where it mixes with the fuel in a certain proportion and burns completely, producing high-temperature, high-pressure gas.

[0055] Furthermore, the high-temperature, high-pressure gas enters the first turbine 6 through a pipe. In the first turbine 6, the gas expands, driving the blades to rotate and converting the internal energy of the gas into mechanical energy, which in turn drives the first generator 13(G) to generate electricity. Although the temperature and pressure of the air after doing work have decreased, it still carries a large amount of residual heat. This part of the air enters the first bottom circulation heater 7 to provide heat for the carbon dioxide working fluid in the bottom circulation.

[0056] The carbon dioxide working fluid in the bottom circulation enters the first bottom circulation heater 7, where it absorbs heat from the air after it has done work in the first turbine 6 of the top circulation, causing the temperature and pressure to rise. Because carbon dioxide has excellent thermal properties, it can efficiently absorb heat.

[0057] Furthermore, the heated carbon dioxide working fluid enters the second turbine 8, where it expands and performs work, converting its internal energy into mechanical energy to drive the second generator 14(G) to generate electricity. After performing work, the temperature and pressure of the carbon dioxide working fluid decrease, but it still retains some energy, and it enters the first regenerator 9.

[0058] In the first regenerator 9, the high-temperature carbon dioxide working fluid at the outlet of the second turbine 8 exchanges heat with the low-temperature carbon dioxide working fluid at the outlet of the second bottom circulation heater 12, releasing some of the waste heat and further reducing the temperature.

[0059] In the second regenerator 10, the carbon dioxide working medium from the outlet of the first regenerator 9 exchanges heat with the carbon dioxide from the outlet of the third compressor 15 to increase the temperature of the carbon dioxide working medium.

[0060] Furthermore, the carbon dioxide working fluid exiting the second regenerator 10 enters the second bottom circulation heater 12, where it exchanges heat with the air from the top circulation and absorbs waste heat. Subsequently, the carbon dioxide working fluid enters the cooler 11, where it exchanges heat with the cooling medium, resulting in a significant temperature reduction and achieving the suction operating state required by the third compressor 15.

[0061] The cooled carbon dioxide working fluid is compressed by the third compressor 15, the pressure increases, and then flows into the pipe between the second regenerator 10 and the second bottom circulation heater 12, re-entering the bottom circulation to complete a complete cycle.

[0062] This application's thermal cycle system adopts a dual-cycle architecture design, realizing the cascade utilization of heat. The top cycle uses air as the working fluid to generate electricity using high-temperature energy, while the bottom cycle uses carbon dioxide as the working fluid to recover the waste heat of the air after the top cycle has done its work, further converting it into electrical energy or other forms of useful energy. At the same time, the setting of multi-stage regenerators (top cycle regenerator 4, first regenerator 9, and second regenerator 10) greatly improves the heat exchange efficiency, enabling the system to make full use of every part of the energy and effectively reduce energy waste.

[0063] Air, as the top-circuit working fluid, has the advantages of being widely available and inexpensive, and can operate stably in high-temperature environments. Carbon dioxide, as the bottom-circuit working fluid, has good thermophysical properties, enabling efficient energy conversion at lower temperatures and pressures. Furthermore, carbon dioxide is chemically stable, has low corrosiveness to equipment, and helps extend equipment lifespan.

[0064] The intercooler 2 lowers the temperature of the air before compression in the top cycle, reducing the energy consumption of the compressor during compression and also reducing the thermal stress on the equipment caused by high temperatures, thus extending the service life of the equipment. The cooler 11 cools the carbon dioxide working fluid in the bottom cycle, allowing the working fluid to enter the third compressor 15 under suitable temperature and pressure conditions, ensuring the stable operation of the bottom cycle and enhancing the stability of the entire system.

[0065] Through efficient energy recovery and utilization, this system reduces fuel consumption. Compared to traditional systems, it significantly reduces fuel consumption while generating the same amount of electricity or providing the same amount of heat. This reduction in fuel consumption directly leads to a decrease in pollutant emissions (such as carbon dioxide and nitrogen oxides). Furthermore, the system uses carbon dioxide as the bottom-cycle working fluid; if carbon dioxide from industrial waste gas is used, it can also be recovered and reused, further reducing greenhouse gas emissions. This aligns with current energy conservation and environmental protection requirements, offering significant social and environmental benefits and contributing to sustainable development in the energy sector.

[0066] refer to Figure 1 , attached Figure 1 The structure and flow of this high-efficiency thermodynamic cycle system are shown in detail. In the diagram, the first compressor 1, intercooler 2, and second compressor 3 are connected in sequence, clearly forming the compression and cooling section of the top cycle. The top cycle regenerator 4 is connected between the outlet of the second compressor 3 and the inlet of the combustion chamber 5 to realize the heat recovery function of the top cycle air. The outlet of the combustion chamber 5 is connected to the first turbine 6, and the outlet of the first turbine 6 is connected to the first bottom cycle heater 7, clearly illustrating the heat transfer path of the air after the top cycle has done work, transferring heat to the carbon dioxide working fluid in the bottom cycle.

[0067] In the bottom circulation section, the outlet of the second turbine 8 is sequentially connected to the first regenerator 9, the second bottom circulation heater 12, the second regenerator 10, the cooler 11, and the third compressor 15, forming a complete bottom circulation cycle path for heating, power generation, waste heat recovery, cooling, and compression of the carbon dioxide working fluid. All components are connected by pipes.

[0068] Continue to refer to Figure 1This application provides a method for operating a supercritical carbon dioxide high-efficiency thermodynamic cycle system for a gas turbine, comprising: compressing air through a compression unit, preheating it through a top cycle regenerator 4, and then burning it in a combustion chamber 5 to generate high-temperature and high-pressure gas, which then enters a first turbine 6 to perform work. After performing work, the air passes through a first bottom cycle heater 7 to heat the bottom cycle working fluid, then flows through the top cycle regenerator 4 to preheat the air at the outlet of the compression unit, and finally flows through a second bottom cycle heater 12 to transfer heat to the bottom cycle working fluid before being discharged from the top cycle system.

[0069] After the bottom-cycle carbon dioxide working fluid flows through the third compressor 15, it is preheated by passing through the second regenerator 10, the second bottom-cycle heater 12, and the first regenerator 9. Then, it flows through the first bottom-cycle heater 7, absorbing heat from the high-temperature air at the top-cycle turbine outlet, and enters the second turbine 8 of the bottom cycle to generate electricity. After flowing through the second turbine 8, the carbon dioxide working fluid passes through the first regenerator 9 and the second regenerator 10 for further preheating. Finally, it exchanges heat with the cooling medium in the cooler 11, resulting in a significant temperature reduction to reach the suction operating state required by the third compressor 15. It then re-enters the bottom cycle, completing a full cycle.

[0070] In summary, the proposed supercritical carbon dioxide high-efficiency thermodynamic cycle system for gas turbines has the following advantages: 1. This system employs a dual-cycle architecture with air as the top-cycle working fluid and carbon dioxide as the bottom-cycle working fluid, coupled with a multi-stage regenerative design, achieving cascaded utilization of heat. The top cycle utilizes the high-temperature energy from fuel combustion to drive the turbine and generate electricity, while the bottom cycle recovers the medium- and low-temperature waste heat from the top cycle exhaust for further power generation. By preheating the combustion air through the top cycle regenerator 4 and recovering the waste heat of the carbon dioxide working fluid through the two-stage regenerators in the bottom cycle, a full-process cascaded heat utilization mode of "high temperature-medium temperature-low temperature" is formed, significantly improving energy conversion efficiency. Compared with traditional thermodynamic cycle systems, it reduces heat waste and significantly improves overall thermal efficiency.

[0071] 2. The system boasts significant environmental advantages. The bottom-circulation working fluid utilizes carbon dioxide from industrial waste gas, achieving carbon dioxide recovery and utilization, effectively reducing greenhouse gas emissions. Simultaneously, due to the overall reduction in system energy consumption and fuel consumption, emissions of pollutants such as nitrogen oxides and sulfides are reduced at the source. Furthermore, using air and carbon dioxide as working fluids, air is widely available and requires no additional treatment, while carbon dioxide is chemically stable and non-corrosive, avoiding the water treatment problems associated with traditional steam cycles and reducing chemical reagent consumption and wastewater discharge.

[0072] 3. Excellent cost-effectiveness. The top cycle uses air as the working fluid, resulting in near-zero cost. The bottom cycle's carbon dioxide can be derived from industrial exhaust gas, further reducing the cost of obtaining the working fluid. Moreover, carbon dioxide is far less corrosive to metal pipes and equipment than water vapor, extending equipment lifespan. The system utilizes high-efficiency plate heat exchangers and specially designed compressors and turbines, reducing equipment failure rates and maintenance costs. Compared to the traditional Rankine cycle, it eliminates the need for a complex water treatment system, saving on equipment investment and operating costs.

[0073] 4. The system possesses excellent stability and adaptability. The intercooler 2 lowers the temperature of the top-cycle compressed air, reducing compressor energy consumption and thermal stress. The cooler 11 ensures that the bottom-cycle carbon dioxide working fluid is compressed at a suitable temperature, improving equipment reliability and extending system lifespan. The dual-cycle architecture can dynamically adjust the working fluid flow rate and operating parameters according to the heat load, maintaining high efficiency even under variable load conditions (such as power generation and industrial heating switching). Furthermore, the system employs a high-efficiency plate heat exchanger and a modular layout, effectively reducing the footprint compared to traditional steam cycle systems. This makes it suitable for space-constrained applications such as ships and distributed energy stations, applicable to multiple fields including power generation, industrial waste heat recovery, and district heating.

[0074] This invention discloses a supercritical carbon dioxide high-efficiency thermodynamic cycle system, wherein the top cycle working fluid is air and the bottom cycle working fluid is carbon dioxide. The system comprises a compression unit (including a first compressor 1, an intercooler 2, and a second compressor 3), a top cycle unit (including a top cycle regenerator 4, a combustion chamber 5, and a first turbine 6), and a bottom cycle unit (including a first bottom cycle heater 7, a second turbine 8, a first regenerator 9, a second bottom cycle heater 12, a second regenerator 10, a cooler 11, and a third compressor 15). After being cooled and compressed by the compression unit, the air is preheated and combusted in the top cycle unit. The first turbine 6 uses the high-temperature and high-pressure gas generated by combustion to generate electricity. The waste heat of the air after doing work is transferred to the first bottom cycle heater 7. In the bottom cycle, the carbon dioxide working fluid undergoes heating, work, waste heat recovery, cooling, and compression in the bottom cycle unit to complete the cycle. This invention utilizes a dual-cycle architecture and multi-stage regenerative design to leverage the properties of air and carbon dioxide as working fluids, thereby achieving cascaded utilization of heat, significantly improving energy conversion efficiency, reducing energy consumption, and offering advantages such as low working fluid cost, long equipment lifespan, and environmental friendliness. It is suitable for energy conversion scenarios such as power generation.

[0075] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of this disclosure, and this disclosure is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this disclosure, and these modifications and improvements are also considered to be within the scope of protection of this disclosure.

Claims

1. A supercritical carbon dioxide high-efficiency thermodynamic cycle system, characterized in that, include: A compression unit is used for staged compression of air, and the compression unit is provided with an air inlet and an air outlet; The top circulation unit is connected to the air outlet of the compression unit and is used to preheat, combust, and convert air working fluid into high-temperature energy for power generation. The top circulation unit is equipped with a high-temperature exhaust outlet. The bottom circulation unit is connected to the high-temperature exhaust outlet of the top circulation unit and is used to receive the waste heat of the high-temperature exhaust from the top circulation unit through heat exchange to heat the carbon dioxide working fluid to form a thermodynamic cycle inside it. The compression unit, the top circulation unit, and the bottom circulation unit constitute a dual-cycle heat cascade utilization architecture.

2. The supercritical carbon dioxide high-efficiency thermodynamic cycle system according to claim 1, characterized in that, The compression unit includes a first compressor, an intercooler, and a second compressor connected in sequence. The first compressor is provided with the air inlet, and the second compressor is provided with the air outlet.

3. The supercritical carbon dioxide high-efficiency thermodynamic cycle system according to claim 1, characterized in that, The top circulation unit includes a top circulation regenerator connected to the air outlet with a cold side inlet, a combustion chamber connected to the cold side outlet of the top circulation regenerator with an inlet, and a first turbine connected to the outlet of the combustion chamber with an inlet. The first turbine is provided with a high-temperature exhaust outlet.

4. The supercritical carbon dioxide high-efficiency thermodynamic cycle system according to claim 3, characterized in that, The bottom circulation unit includes a first bottom circulation heater whose hot-side inlet is connected to the high-temperature exhaust outlet of the first turbine, a second turbine whose inlet is connected to the cold-side outlet of the first bottom circulation heater, a first regenerator, a second regenerator and a cooler connected in sequence to the outlet of the second turbine, a third compressor whose inlet is connected to the outlet of the cooler and whose outlet is connected to the cold-side inlet of the second regenerator, and a second bottom circulation heater. The hot-side inlet of the second bottom circulation heater is connected to the hot-side outlet of the top circulation regenerator, the cold-side outlet of the second bottom circulation heater is connected to the cold-side inlet of the first regenerator, and the cold-side inlet of the second bottom circulation heater is connected to the cold-side outlet of the second regenerator.

5. The supercritical carbon dioxide high-efficiency thermodynamic cycle system according to claim 3, characterized in that, Also includes: The first generator is connected to the first turbine drive.

6. The supercritical carbon dioxide high-efficiency thermodynamic cycle system according to claim 4, characterized in that, Also includes: The second generator is connected to the second turbine drive.

7. The supercritical carbon dioxide high-efficiency thermodynamic cycle system according to claim 2, characterized in that, The intercooler includes a plate heat exchanger.

Images