Allam cycle power generation system and method integrated with CO2 energy storage

Abstract

The invention belongs to the field of electric power, and discloses an Allam cycle power generation system integrated with CO2 energy storage, which comprises an Allam cycle and a CO2 energy storage system, the Allam circulating system specifically comprises a fuel compressor, a combustor, a gas turbine, a heat exchanger, a flue gas cooler, a gas-liquid separator, a CO2 compressor, a flow divider, a CO2 condenser A, a CO2 pump, an O2 compressor and a flow combiner A; the CO2 energy storage system comprises a confluence device B, a CO2 condenser B, a low-pressure CO2 storage tank, an evaporator, a compressor, an intercooler, a high-pressure CO2 storage tank, a reheater, an expansion machine and a H2O condenser. According to the Allam cycle power generation system integrated with the CO2 energy storage technology, transcritical CO2 is adopted as working fluid in Allam cycle, cycle working media can be directly provided for the energy storage system, and cost is effectively saved. The system can solve the problems that an oxygen-enriched combustion power plant is low in power generation efficiency and poor in economical efficiency, and efficient carbon emission reduction of the power plant can be achieved easily.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the field of electric power technology, and in particular relates to an Allam cycle power generation system and method with integrated CO2 energy storage. Background Art

[0002] As energy demand continues to grow, environmental issues caused by large amounts of carbon emissions from power plants have attracted widespread attention. In order to reduce carbon emissions, it is essential to develop carbon capture, utilization and storage (CCUS) technology. Oxygen-enriched combustion is one of the most promising CCUS technologies that can be applied to power generation systems. However, the oxygen production process and carbon capture unit in traditional oxy-combustion power plants cause additional power consumption and increase power plant costs. Therefore, exploring efficient and economical oxy-combustion power generation systems is of great significance for the large-scale promotion and application of CCUS technology.

[0003] The Allam cycle is an oxygen-enriched combustion power generation system that uses transcritical CO2 as the working fluid, which has the advantages of high efficiency and low cost. The combustion pressure of the Allam cycle is usually 280bar-320bar, and the combustion temperature is 1100℃-1200℃. Since the combustion process of the Allam cycle uses high-purity O2, the flue gas components after combustion are basically H2O and CO2. After separating H2O, high-purity CO2 can be obtained. Studies have shown that the carbon capture rate of the Allam cycle can reach nearly 100%. In addition, the pressure of the flue gas at the outlet of the gas turbine of the Allam cycle is about 30bar, so the CO2 in the flue gas is easily compressed to above the critical pressure, and then liquefied at room temperature, which greatly reduces the compression power consumption and condensation energy consumption in the carbon capture process. Most of the liquefied CO2 is pressurized by a pump and then circulated into the burner to adjust the combustion temperature, and the remaining CO2 can be used or sealed.

[0004] Using renewable energy to generate electricity and promoting the low-carbon transformation of the energy structure are also important measures to address climate change. Since renewable energy is generally intermittent and unstable, large-scale renewable energy grid-connected power generation places high demands on the flexibility of power plants. For fossil energy power generation systems, their peak-shaving capabilities should also be increased to meet the needs of the power grid while providing guarantees for the smooth transition of the energy structure and helping to achieve carbon emission reduction. The application of energy storage technology is an effective measure to achieve a balance between electricity supply and demand. Integrating energy storage systems with oxygen-enriched combustion power generation systems is conducive to safer and more flexible operation of power plants.

[0005] Patent 202123269415.3 and Patent 202110945358.1 disclose an oxygen-enriched combustion power generation system coupled with air energy storage, which improves the deep peak-shaving capability of the power plant to a certain extent. In addition to air, CO2 can also be used as the working fluid of the energy storage system. The CO2 energy storage system includes two processes: charging and discharging. When electricity consumption is low, the CO2 is compressed using the electricity generated by the power plant. The electrical energy is stored in the high-pressure CO2 in the form of pressure energy. During peak electricity consumption, the high-pressure CO2 is passed through a turbine to generate electricity and release the stored electrical energy. Compared with air, CO2 has better thermophysical properties and is easier to achieve phase transitions between gaseous, liquid and supercritical states, reducing energy storage costs. In addition, by combining CO2 energy storage technology with an oxygen-enriched combustion power plant, part of the CO2 obtained by the carbon capture unit in the power plant can be directly provided to the energy storage system without the need to additionally prepare the working fluid of the energy storage system, which is conducive to the full utilization of CO2 and promotes the application of CCUS technology.

[0006] In order to achieve efficient and low-cost carbon emission reduction while ensuring the peak-shaving capacity of the power plant, an Allam cycle power generation system integrated with a CO2 energy storage system was constructed. Part of the CO2 separated from the flue gas after combustion in the Allam system can provide working fluid for the energy storage system, increasing the utilization rate of CO2. At the same time, it can balance the power load, reduce peaks and fill valleys, and form a stable power supply.

[0007] In view of the above analysis, the technical problems that need to be solved urgently in the prior art are:

[0008] Oxygen-enriched combustion power plants have the problems of low power generation efficiency and poor economy. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides an Allam cycle power generation system with integrated CO2 energy storage.

[0010] The present invention is implemented as follows: an Allam cycle power generation system with integrated CO2 energy storage, characterized in that the Allam cycle power generation system with integrated CO2 energy storage includes: Allam cycle, CO2 energy storage system. The Allam cycle system specifically includes a fuel compressor, a burner, a gas turbine, a heat exchanger, a flue gas cooler, a gas-liquid separator, a CO2 compressor, a splitter, a CO2 condenser A, a CO2 pump, an O2 compressor and a combiner A; the CO2 energy storage system includes a combiner B, a CO2 condenser B, a low-pressure CO2 storage tank, an evaporator, a compressor, an intermediate cooler, a high-pressure CO2 storage tank, a reheater, an expander and an H2O condenser.

[0011] Furthermore, in the Allam cycle system, the inlet of the burner is connected to the outlet of the fuel compressor and the outlet of the cold stream of the heat exchanger respectively, and the outlet of the burner is connected to the inlet of the gas turbine; the hot stream inlet of the heat exchanger is connected to the gas turbine, and the cold stream inlet is connected to the outlet of the combiner A; the hot stream outlet of the heat exchanger is connected to the inlet of the flue gas condenser, and the cold stream outlet is connected to the inlet of the burner; the heat exchanger is used for heat exchange between the flue gas at the outlet of the gas turbine and the mixed stream of CO2 and O2; the flue gas cooler is used to further cool the flue gas and send the cooled flue gas to the gas-liquid separator; the gas-liquid separator is used The water and CO2 in the flue gas are separated, the separated water is discharged from the system, and the separated CO2 is sent to the CO2 compressor; the CO2 compressor is used to compress CO2 to near the critical pressure, and send the compressed CO2 to the diverter; the outlet of the diverter is respectively connected to the CO2 energy storage system and the CO2 condenser A; the CO2 condenser A is used to cool CO2 to liquid state, and the liquid CO2 enters the CO2 compression pump and is compressed to the combustion pressure; the inlet of the combiner A is respectively connected to the outlet of the CO2 compression pump and the outlet of the O2 compressor, and the outlet is connected to the cold stream inlet of the heat exchanger B; the O2 compressor is used to compress O2 to the combustion pressure.

[0012] Furthermore, in the CO2 energy storage system, the inlet of the combiner B is respectively connected to the expander outlet and the diverter outlet, and the outlet is connected to the CO2 condenser B; the CO2 condenser B, the low-pressure CO2 storage tank, the evaporator, and the compressor are connected in this order; the hot flow stream inlet of the intercooler is connected to the compressor outlet, and the cold flow stream inlet is connected to the cooler outlet; the hot flow stream outlet of the intercooler is connected to the high-pressure CO2 storage tank, and the cold flow stream outlet is connected to the hot flow stream inlet of the reheater; the hot flow stream inlet of the reheater is connected to the cold flow stream outlet of the intercooler, and the cold flow stream inlet is connected to the high-pressure CO2 storage tank outlet; the hot flow stream outlet of the reheater is connected to the cooler inlet, and the cold flow stream outlet is connected to the expander outlet.

[0013] Furthermore, the compressor is used to compress CO2 to a high-pressure storage pressure, and the intercooler uses water to cool the CO2 at the compressor outlet; the expander is used to expand CO2 to generate electricity, and the reheater is used to increase the temperature of CO2 at the expander inlet to improve the power generation efficiency; the cooler is used to further cool the heat exchange medium at the reheater outlet, and then send it to the intercooler for heat exchange.

[0014] Furthermore, a possible specific operation process of the CO2 energy storage system is:

[0015] When the electricity load is at a low point, the CO2 energy storage system starts to charge. The liquid CO2 in the low-pressure CO2 storage tank is first heated to gaseous state by a preheater, and then passes through a compressor and an intercooler in sequence. At this time, the CO2 is in a high-pressure liquid state and enters the high-pressure CO2 storage tank for storage. The power required by the compressor is provided by the gas turbine in the Allam cycle.

[0016] When the electricity load is at its peak, the CO2 energy storage system starts to discharge. The CO2 in the high-pressure CO2 storage tank passes through the reheater expander in turn to release the stored electrical energy. The CO2 at the expander outlet is mixed with part of the CO2 separated in the Allam cycle. The mixed CO2 is condensed into liquid through the CO2 condenser B, and the liquid CO2 enters the low-pressure CO2 storage tank and is stored.

[0017] Furthermore, the fuel compressor inlet fluid includes gaseous fuels such as natural gas, coal gasification gas, and biomass gasification gas.

[0018] Furthermore, the CO2 energy storage system may adopt two-stage compression and two-stage expansion, or multi-stage compression and multi-stage expansion, with an intercooler provided at the outlet of each compressor and a reheater provided at the inlet of each expander.

[0019] Furthermore, a compressor is arranged after the combiner B in the CO2 energy storage system to further compress the CO2 to a supercritical state, and the energy storage unit uses supercritical CO2 as a working fluid.

[0020] Furthermore, the heat exchange medium in the CO2 energy storage system can be water, heat transfer oil, salt solution, etc.

[0021] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0022] First, in response to the defects and improvement needs of the prior art, the present invention provides an Allam cycle power generation system with integrated CO2 energy storage technology. The Allam cycle uses transcritical CO2 as the working fluid, which can directly provide circulating working fluid for the energy storage system, effectively saving costs. This system will solve the problems of low power generation efficiency and poor economy of oxygen-enriched combustion power plants, and will help achieve efficient carbon emission reduction in power plants. The application of energy storage technology improves the peak-shaving capacity of power plants, providing support for increasing renewable energy power generation and promoting a smooth transformation of the energy structure.

[0023] The present invention utilizes the advantages of the Allam cycle, which is efficient, economical and has a high carbon capture rate, is conducive to the efficient, economical and flexible application of oxygen-enriched combustion power generation technology, and has positive significance for achieving carbon emission reduction in power plants and reducing power generation costs.

[0024] The present invention couples the CO2 energy storage system with the biomass gasification Allam cycle, utilizing the characteristic of the Allam cycle of using transcritical CO2 as a working fluid, solving the problem of the source of the working medium of the energy storage system, improving the utilization rate of CO2, and increasing the stability of the power generation system.

[0025] The present invention utilizes excess electricity as energy input for the energy storage unit during low electricity consumption periods, and releases the electricity during peak electricity consumption periods, thereby achieving the purpose of storing excess electricity and alleviating power supply pressure during peak periods, thereby ensuring the smooth operation of the power plant.

[0026] The present invention adopts compressed CO2 as the working fluid of the energy storage unit, which is easy to achieve phase transition, has a compact system structure, and reduces investment costs.

[0027] In addition to electricity, the product of the present invention also includes liquid CO2, which improves the economic benefits and environmental friendliness of the power plant and is conducive to the realization of the "dual carbon" goal.

[0028] Second, as a new type of compressed gas energy storage technology, the compressed CO2 carbon energy storage system proposed in the present invention has the advantages of high energy storage density, low economic cost, long operating life, negative carbon emissions, etc., which is suitable for the construction of large-scale long-term energy storage systems and sustainable development in my country. Secondly, the system is not restricted by geographical conditions, the working fluid is easy to obtain, the working condition is stable, the charging and discharging state can be switched freely, the cost is low and the efficiency is high, the project construction period is short, the service life is long, and the cycle efficiency is maintained above 60%. In addition, the system can be matched with new energy sources such as biomass power generation, effectively overcoming its power generation volatility and intermittency, and can also be used in conjunction with generator sets as power compensation during flexible peak-shaving operation of power generation, greatly improving the peak-shaving capacity of the unit and the comprehensive utilization efficiency of energy. At the same time, the system can also be combined with the carbon dioxide capture and storage system to realize the integrated recovery, utilization and treatment of carbon dioxide, which has broad application prospects and is expected to become one of the key forces to support the achievement of my country's "dual carbon" goals. Therefore, the research and application of compressed carbon dioxide energy storage coupled with the Allam cycle system can not only fill the research gap in this field at home and abroad, but also provide important solutions for the future energy system dominated by renewable energy and the multi-energy synergistic and complementary network.

[0029] The technical solution of the present invention solves a technical problem that people have been eager to solve but have never succeeded in solving: the problem of low-pressure side CO2 liquefaction: In traditional compressed carbon dioxide energy storage systems, the temperature of the cold required for low-pressure side CO2 liquefaction is below zero, and the heat exchange conditions are harsh, making it difficult to achieve. This system uses a throttle valve to adjust the low-pressure side CO2 outlet pressure, further reducing the CO2 temperature, and recovering part of the cold for the liquefaction of the CO2 at the expander outlet, effectively solving the problem of uneven energy matching in the cold storage and heat exchange process.

[0030] System cost and complexity: The low-pressure and high-pressure storage tanks of conventional compressed carbon dioxide energy storage are both constant-volume containers. The tank pressure changes when the working fluid flows in / out. Generally, it is considered to store the CO2 liquefied on the low-pressure side and the high-pressure side, which requires additional refrigeration cycles or cryogenic working fluids to achieve liquefaction, further increasing the system cost and complexity. This system effectively utilizes the CO2 after work to achieve organic coupling between the energy storage system and the power generation system, reducing the system cost and complexity.

[0031] Problem of efficient absorption and utilization of compression heat: The system arranges multiple heat storage units in series to absorb CO2 compression heat, uses water as the heat storage medium, and takes advantage of the low cost of water to achieve efficient absorption and utilization of compression heat, thereby improving the energy utilization rate of the system.

[0032] Third, the gas turbine cycle system in the existing technology has the problems of low efficiency and high CO2 emissions, insufficient waste heat utilization rate of exhaust gas, and poor environmental protection. To address this problem, the Allam cycle system innovatively uses CO2 as the main working fluid, improves system efficiency through thermodynamic properties under supercritical conditions, and realizes the capture and recycling of CO2. The system adopts a fully closed cycle structure, through the close coupling of the burner, gas turbine and heat exchanger, it not only improves the fuel utilization rate, but also simplifies the waste heat utilization process, effectively solving the limitations brought by the complexity of traditional processes.

[0033] Traditional energy storage technology is not efficient enough when dealing with large-scale energy storage and conversion. At the same time, the separation of energy storage and power generation systems limits the overall energy utilization efficiency. In addition, the storage stability of supercritical CO2 also faces challenges. The CO2 energy storage system achieves efficient storage and flexible deployment of energy through the coordinated design of low-pressure and high-pressure storage tanks. The condenser, evaporator and other components in the system optimize the phase conversion process of CO2, enhance the stability of the system, and significantly improve the energy conversion efficiency through the integrated design of energy storage and power generation.

[0034] Traditional heat exchangers have large heat losses under high temperature and high pressure conditions, and the equipment is large in size and has insufficient pressure resistance, which cannot meet the needs of efficient circulation. In response to these problems, the heat exchanger in this system adopts a hot stream and cold stream separation design, optimizes the flow channel structure, and greatly improves the heat exchange efficiency. At the same time, the compact design reduces the size and material cost of the equipment, and through the use of high temperature and high pressure resistant materials, the heat exchanger can operate stably for a long time in a supercritical CO2 environment, thus laying the foundation for improving the overall efficiency of the system.

[0035] The problems of low gas-liquid separation efficiency and large energy loss restrict the performance of traditional power generation systems. By optimizing the separation path and fluid control design, the gas-liquid separator achieves high-purity and efficient separation of CO2, meeting the system's demand for pure working fluid. In addition, the expander makes full use of the expansion process of high-pressure gas to recover energy, efficiently converts pressure energy into mechanical energy, and combines thermal management strategies to improve the efficiency of heat recovery. These improvements further improve the energy utilization and operational reliability of the system, and provide support for new integrated power generation and energy storage technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is an Allam cycle flow chart of integrated CO2 energy storage provided by an embodiment of the present invention;

[0037] Figure 2 is a flow chart of the biomass gasification Allam cycle of the integrated CO2 energy storage system provided in an embodiment of the present invention;

[0038] Figure 3 is an Allam cycle flow chart of an integrated two-stage compression / expansion CO2 energy storage system provided by an embodiment of the present invention;

[0039] Figure 4 is an Allam cycle flow chart of an integrated three-stage compression / expansion CO2 energy storage system provided by an embodiment of the present invention;

[0040] Figure 5 The Allam-CCES system provided by the embodiment of the present invention Damage distribution diagram;

[0041] Figure 6 is a diagram showing the effect of low pressure storage pressure on RTE and EVR in the Allam-CCES system provided by an embodiment of the present invention;

[0042] Figure 7 is a diagram showing the effect of high pressure storage pressure on RTE and EVR in the Allam-CCES system provided by an embodiment of the present invention;

[0043] Figure 8 is a purchase cost diagram of Allam-CCES system components provided by an embodiment of the present invention;

[0044] Fig. 9 This is a disassembly diagram of the GWP results of the charging process of the integrated system provided by an embodiment of the present invention;

[0045] Fig.10 This is a disassembly diagram of the GWP results of the integrated system discharge process provided by an embodiment of the present invention;

[0046] In the figure: 1. fuel compressor; 2. burner; 3. gas turbine; 4. heat exchanger; 5. flue gas cooler; 6. gas-liquid separator; 7. CO2 compressor; 8. splitter; 9. CO2 condenser A; 10. CO2 pump; 11. O2 compressor; 12. combiner A; 13. combiner B; 14. CO2 condenser B; 15. low-pressure CO2 storage tank; 16. evaporator; 17. compressor; 18. intermediate cooler Cooler; 19. High-pressure CO2 storage tank; 20. Reheater; 21. Expander; 22. Cooler; 23. Biomass gasifier; 24. Gasification gas cooler; 25. Secondary compressor; 26. Secondary intercooler; 27. Secondary reheater; 28. Secondary expander; 29. ​​Cooler B; 30. Third-stage compressor; 31. Third-stage intercooler; 32. Third-stage reheater; 33. Third-stage expander; 34. Cooler C. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] like Figure 1As shown, an embodiment of the present invention provides an Allam cycle power generation system with integrated CO2 energy storage, including: Allam cycle, CO2 energy storage system. The Allam cycle system specifically includes a fuel compressor 1, a burner 2, a gas turbine 3, a heat exchanger 4, a flue gas cooler 5, a gas-liquid separator 6, a CO2 compressor 7, a splitter 8, a CO2 condenser A9, a CO2 pump 10, an O2 compressor 11 and a combiner A12; the inlet of the burner 2 is respectively connected to the outlet of the fuel compressor 1 and the outlet of the cold stream of the heat exchanger 4, and the outlet of the burner 2 is connected to the inlet of the gas turbine 3; the hot stream inlet of the heat exchanger 4 is connected to the gas turbine 3, and the cold stream inlet is connected to the outlet of the combiner A12; the hot stream outlet of the heat exchanger 4 is connected to the inlet of the flue gas condenser 5, and the cold stream outlet is connected to the inlet of the burner 2; the heat exchanger 4 is used for heat exchange between the flue gas at the outlet of the gas turbine 3 and the mixed stream of CO2 and O2; the flue gas cooler The device 5 is used to further cool the flue gas and send the cooled flue gas to the gas-liquid separator 6; the gas-liquid separator 6 is used to separate water and CO2 in the flue gas, the separated water is discharged from the system, and the separated CO2 is sent to the CO2 compressor 7; the CO2 compressor 7 is used to compress CO2 to near the critical pressure, and send the compressed CO2 to the diverter 8; the outlet of the diverter 8 is respectively connected to the CO2 energy storage system and the CO2 condenser A9; the CO2 condenser A9 is used to cool CO2 to a liquid state, and the liquid CO2 enters the CO2 compression pump 10 and is compressed to the combustion pressure; the inlet of the combiner A12 is respectively connected to the outlet of the CO2 compression pump 10 and the outlet of the O2 compressor 11, and the outlet is connected to the cold stream inlet of the heat exchanger B4; the O2 compressor 11 is used to compress O2 to the combustion pressure;

[0049] The CO2 energy storage system includes a combiner B13, a CO2 condenser B14, a low-pressure CO2 storage tank 15, an evaporator 16, a compressor 17, an intercooler 18, a high-pressure CO2 storage tank 19, a reheater 20, an expander 21 and a H2O condenser 22; the inlet of the combiner B13 is respectively connected to the outlet of the expander 21 and the outlet of the splitter 8, and the outlet is connected to the CO2 condenser B14; the CO2 condenser B14, the low-pressure CO2 storage tank 15, the evaporator 16 and the compressor 17 are connected in this order; The hot flow inlet of the intercooler 18 is connected to the outlet of the compressor 17, and the cold flow inlet is connected to the outlet of the cooler 22; the hot flow outlet of the intercooler 18 is connected to the high-pressure CO2 storage tank 19, and the cold flow outlet is connected to the hot flow inlet of the reheater 20; the hot flow inlet of the reheater 20 is connected to the cold flow outlet of the intercooler 18, and the cold flow inlet is connected to the outlet of the high-pressure CO2 storage tank 19; the hot flow outlet of the reheater 20 is connected to the inlet of the cooler 22, and the cold flow outlet is connected to the outlet of the expander 21.

[0050] The compressor 17 is used to compress CO2 to a high-pressure storage pressure, and the intercooler 18 uses water to cool the CO2 at the compressor outlet; the expander 21 is used to expand CO2 to generate electricity, and the reheater 20 is used to increase the temperature of CO2 at the expander inlet to improve the power generation efficiency; the cooler 22 is used to further cool the heat exchange medium at the outlet of the reheater 20, and then send it to the intercooler 18 for heat exchange.

[0051] A possible specific operation process of the CO2 energy storage system is:

[0052] When the electricity load is at a low point, the CO2 energy storage system starts to charge. The liquid CO2 in the low-pressure CO2 storage tank 15 is first heated to a gas state by the preheater 16, and then passes through the compressor 17 and the intercooler 18 in sequence. At this time, the CO2 is in a high-pressure liquid state and enters the high-pressure CO2 storage tank 19 for storage. The electricity required by the compressor 17 is provided by the gas turbine 3 in the Allam cycle.

[0053] When the electricity load is at its peak, the CO2 energy storage system starts to discharge. The CO2 in the high-pressure CO2 storage tank 19 passes through the reheater 20 and the expander 21 in turn to release the stored electrical energy. The CO2 at the outlet of the expander 21 is mixed with part of the CO2 separated in the Allam cycle. The mixed CO2 is condensed into liquid through the CO2 condenser B (14). The liquid CO2 enters the low-pressure CO2 storage tank 15 and is stored.

[0054] The fuel compressor inlet fluid includes gaseous fuels such as natural gas, coal gasification gas, and biomass gasification gas.

[0055] The CO2 energy storage system may adopt two-stage compression and two-stage expansion, or multi-stage compression and multi-stage expansion, with an intercooler provided at the outlet of each compressor and a reheater provided at the inlet of each expander.

[0056] A compressor is arranged after the combiner B in the CO2 energy storage system to further compress the CO2 to a supercritical state, and the energy storage unit uses supercritical CO2 as a working fluid.

[0057] The heat exchange medium in the CO2 energy storage system can be water, heat transfer oil, salt solution, etc.

[0058] The Allam cycle power generation system with integrated CO2 energy storage of the present invention realizes efficient utilization and storage of energy by combining the CO2 energy storage system with the Allam cycle. The Allam cycle part utilizes components such as a fuel compressor, a burner, and a gas turbine to generate high-temperature and high-pressure flue gas, and the flue gas expands in the gas turbine to do work and generate electricity. The expanded flue gas is cooled by a heat exchanger and a flue gas cooler, and water and CO2 are separated in a gas-liquid separator. CO2 circulates in the system, and after compression, diversion, and cooling, it becomes liquid, and then is pressurized to the pressure required for combustion by a CO2 compression pump, and sent back to the burner to participate in the cycle.

[0059] The design of the CO2 energy storage system allows energy to be stored when the power load is low and released when the power demand is peak. At low times, the CO2 energy storage system uses a preheater to heat the liquid CO2 in the low-pressure CO2 storage tank to a gas state, and then undergoes multi-stage compression and intermediate cooling to eventually form high-pressure liquid CO2 and store it in a high-pressure CO2 storage tank. The energy required for the compression process is provided by the gas turbine in the Allam cycle. At peak times, the CO2 energy storage system releases CO2 from the high-pressure CO2 storage tank, which is heated by the reheater and expanded in the expander to generate electricity. The expanded CO2 is mixed with part of the CO2 separated by the Allam cycle and condensed, and returned to the low-pressure storage tank for standby use.

[0060] The system achieves efficient energy storage and power generation of the CO2 cycle through position and connection relationships. The compressor, expander, condenser and reheater work together to dynamically adjust the CO2 storage and release process under different load conditions. CO2 has high energy conversion efficiency during compression and expansion, reducing energy loss in traditional energy storage methods.

[0061] Ultimately, the integrated system has the ability to recycle CO2 energy storage and power generation, reducing CO2 emissions in traditional power generation methods and improving the cleanliness and efficiency of the power generation system.

[0062] Embodiment 1:

[0063] This embodiment provides a biomass gasification Allam cycle with an integrated CO2 energy storage system, such as Figure 2 As shown, it includes a biomass gasifier 23, a synthesis gas cooler 24, a fuel compressor 1, a burner 2, a gas turbine 3, a heat exchanger 4, a flue gas cooler 5, a gas-liquid separator 6, a CO2 compressor 7, a splitter 8, a CO2 condenser A9, a CO2 pump 10, an O2 compressor 11, a combiner A12, a combiner B13, a CO2 condenser B14, a low-pressure CO2 storage tank 15, a preheater 16, a compressor 17, an intermediate cooler 18, a high-pressure CO2 storage tank 19, a reheater 20, an expander 21 and a cooler 22.

[0064] Among them, the outlet of the biomass gasifier 23 is connected to the hot flow inlet of the synthesis gas cooler 24. The biomass gasifier 23 is used for the reaction of biomass raw materials with gasifying agents to generate gasified synthesis gas. The synthesis gas cooler 24 is used for heat exchange between the high-temperature synthesis gas at the outlet of the biomass gasifier 23 and the gasifying agent, and the gasifying agent is heated to the gasification temperature. The cooled synthesis gas is sent to the fuel compressor 1, and the fuel compressor 1 is used to compress the biomass gasification synthesis gas to the combustion pressure.

[0065] The inlet of the burner 2 is connected to the cold stream outlet of the heat exchanger 4 and the outlet of the fuel compressor 1 respectively; the burner 2 is used for the combustion of biomass gasification synthesis gas, and the flue gas after combustion is sent to the gas turbine 3 for expansion and work; the outlet of the gas turbine 3 is connected to the hot stream inlet of the heat exchanger 4; the heat exchanger 4 is used for heat exchange between the expanded flue gas and the mixed stream of CO2 and O2, and the cooled flue gas is sent to the flue gas cooler 5 for further cooling; the outlet of the flue gas cooler 5 is connected to the gas-liquid separator 6; the gas-liquid separator 6 is used to separate water and CO2 in the flue gas, and the separated water is discharged from the system, and the remaining CO2 is discharged from the system. O2 is sent to the CO2 compressor 7; the CO2 compressor 7 is used to compress CO2 to above the critical pressure, and send the compressed CO2 to the splitter 8; the splitter 8 is used to divide CO2 into two streams, one of which is sent to the CO2 energy storage system as a working medium, and the other is sent to the CO2 condenser 9 to be cooled into a liquid state; the outlet of the condenser 9 is connected to the inlet of the CO2 pump 10; the CO2 pump 10 is used to compress the liquid CO2 to the combustion pressure; the inlet of the combiner A12 is respectively connected to the outlets of the CO2 pump 10 and the O2 compressor 11; the O2 compressor 11 is used to compress O2 to the combustion pressure;

[0066] The inlet of the combiner B13 is connected to the splitter 8 and the expander 21 respectively, and part of the CO2 captured in the Allam cycle is mixed with the circulating CO2 in the CO2 energy storage system and sent to the CO2 low-pressure storage tank 15.

[0067] During charging, part of the CO2 in the low-pressure CO2 storage tank 15 is captured and sealed, and the remaining part is sent to the evaporator 16 to be heated to a gaseous state; the gaseous CO2 at the outlet of the evaporator 16 enters the compressor 17 to be pressurized; the outlet of the compressor 17 is connected to the intercooler 18; the first-stage intercooler 18 is used to cool the compressed CO2, and then send the high-pressure CO2 to the high-pressure CO2 storage tank 19 for storage.

[0068] During discharge, the CO2 in the high-pressure CO2 storage tank 19 is first heated by the reheater 20, and then enters the expander 21 to expand and generate electricity; the outlet of the expander 21 is connected to the combiner B13.

[0069] The inlet of the cooler 22 is connected to the hot stream outlet of the reheater 20, and the outlet is connected to the cold stream inlet of the intercooler 18; the cooler 22 is used to cool the heat transfer medium that exchanges heat with CO2 in the CO2 energy storage system.

[0070] Embodiment 2:

[0071] This example provides an Allam cycle integrated with a two-stage compression turbine CO2 energy storage system. Figure 3 As shown, the difference from the energy storage system of Example 1 is that the CO2 energy storage system of Example 2 adopts two-stage compression and two-stage expansion.

[0072] During charging, part of the CO2 in the low-pressure CO2 storage tank 15 is sealed, and the remaining part is sent to the evaporator 16 to be heated into a gaseous state; the outlet of the evaporator 16 is connected to the compressor 17 in turn; the outlet of the compressor 17 is connected to the hot flow inlet of the intercooler 18; the intercooler 18 is used to cool the compressed CO2 and then send the CO2 to the secondary compressor 25; the outlet of the secondary compressor 25 is connected to the hot flow inlet of the secondary intercooler 26; the secondary intercooler 26 is used to cool the compressed CO2, and the cooled CO2 is sent to the high-pressure CO2 storage tank 19 for storage.

[0073] During discharge, the CO2 in the high-pressure CO2 storage tank 19 is first heated by the secondary reheater 27, and then enters the secondary expander 28 to expand and generate electricity; the outlet of the secondary expander 28 is connected to the cold flow inlet of the reheater 20; the reheater 20 is used to heat the expanded CO2 and send it to the expander 25 for further expansion and power generation.

[0074] The inlet of cooler 22 is connected to the hot stream outlet of reheater 20, and the outlet is connected to the cold stream inlet of intercooler 18; the inlet of cooler B29 is connected to the hot stream outlet of secondary reheater 27, and the outlet is connected to the cold stream inlet of secondary intercooler 26; the cooler 22 and cooler B29 are used to cool the heat exchange medium.

[0075] Embodiment three:

[0076] This example provides an Allam cycle integrated with a three-stage compression turbine CO2 energy storage system. Figure 4 As shown, the difference from the first embodiment is that the CO2 energy storage system adopts three-stage compression and three-stage expansion.

[0077] During charging, the CO2 in the low-pressure CO2 storage tank 15 is first gasified by the evaporator 16, and the gaseous CO2 at the outlet of the evaporator 16 passes through the compressor 17, the intercooler 18, the secondary compressor 25, the secondary intercooler 26, the tertiary compressor 30 and the tertiary intercooler 31 in sequence, and then enters the high-pressure CO2 storage tank for storage; the CO2 at the outlet of each compressor needs to enter the corresponding intercooler for cooling, and the compression heat is recovered by the heat exchange medium in the energy storage system.

[0078] During discharge, the CO2 in the high-pressure CO2 storage tank undergoes three-stage expansion to convert the stored pressure energy into electrical energy; in order to ensure the expansion power generation efficiency, the CO2 is first heated by a reheater before entering the expander; in the reheater, the CO2 exchanges heat with the circulating heat exchange medium in the energy storage system, absorbing the compression heat stored in the heat exchange medium during charging; the CO2 passes through the three-stage reheater 32, the three-stage expander 33, the two-stage reheater 27, the two-stage expander 28, the reheater 20 and the expander 21 in sequence, and then is mixed with the CO2 in the Allam cycle, liquefied by the CO2 condenser B14, and enters the low-pressure CO2 storage tank 15 for storage.

[0079] Cooler 22, cooler B29 and cooler C34 in the CO2 energy storage system are used to cool the heat exchange medium.

[0080] The specific application areas of the present invention are mainly concentrated in energy conversion and energy storage technology. The system can improve the performance of the compressed carbon dioxide energy storage system, and through coupling with the biomass gasification Allam cycle system, it can achieve cascade utilization of energy and improve system efficiency. Specific applications include:

[0081] Power storage: The system can be used as a form of power storage, especially in situations where large-scale energy storage solutions are required, such as grid load balancing and the integration of renewable energy sources.

[0082] Biomass energy utilization: By coupling with the biomass gasification Allam cycle system, this technology can improve the utilization efficiency of biomass energy and achieve zero-carbon emission power generation technology.

[0083] CO2 capture and utilization: The system is deeply coupled with the CO2 capture of the Allam cycle system, and the captured carbon dioxide is used in the energy storage system. The integrated system has the ability to recycle CO2 energy storage and power generation, reducing CO2 emissions in traditional power generation methods and improving the cleanliness and efficiency of the power generation system.

[0084] The present invention constructs a biomass gasification Allam cycle coupled compressed CO2 energy storage (Allam-CCES) system and calculates and analyzes the basic performance parameters of the system.

[0085] During the charging process, the net power generation of the Allam-CCES system is 74.95MW, and the power generation efficiency is 36.43%; during the discharge, the net power generation and power generation efficiency of the system are 81.17MW and 39.45%, respectively. The results show that coupling with the CCES system can improve the flexibility of biomass gasification Allam cycle power generation and has a certain peak load capacity. The round-trip efficiency of CCES in the coupled system is 62.04%

[0086] Table 1: Energy analysis results of the Allam-CCES system

[0087]

[0088] Allam-CCES system components Analysis results and system The loss distribution is shown in Table 2 and Figure 5 The total system The loss was 254.86MW, of which the CCES system The loss rate was 15.6%, and the rest The damage comes from the components of the Allam cycle. Among all the components in the system, the gasifier The largest proportion of losses was 21.8%, followed by condenser 1, cooler 2 and burner, accounting for the total Losses were 17.8%, 17.7% and 17.4%.

[0089] Table 2 Allam-CCES system Analyze the results

[0090]

[0091]

[0092] When the low-pressure storage pressure is in the range of 72.3 bar to 78.0 bar, the changing trends of the round-trip efficiency and energy storage density in the Allam-CCES system are as follows: Figure 6 As shown. Due to the sudden change in energy consumption of compressor 1 caused by the phase transition of CO2 as the pressure increases, the round-trip efficiency of CCES in the coupled system also suddenly decreases between the low-pressure storage pressure of 74.5bar-75.0bar. When the low-pressure storage pressure is 74.5bar, the round-trip efficiency reaches a maximum value of 90.71%. As the low-pressure storage pressure increases from 72.3bar to 78.0bar, the energy storage density increases from 2.72kWh / m3 to 2.91kWh / m3, and the growth rate gradually slows down. This trend is the same as the trend of energy storage density change of a single CCES system, which is the result of the degree of reduction in expander power being less than the degree of reduction in the volume of the low-pressure storage tank.

[0093] The results of the effect of high pressure storage pressure on the round trip efficiency and energy storage density in the Allam-CCES system are shown in Figure 7 In the coupled system, it can be seen that the higher the high-pressure storage pressure, the lower the round-trip efficiency of the system. When the high-pressure storage pressure increases from 220bar to 400bar, the round-trip efficiency decreases from 66.10% to 60.00%, and the rate of decrease in the round-trip efficiency is getting slower and slower. The heat consumption of the evaporator is not considered in the Allam-CCES coupled system, and the round-trip efficiency of CCES is only related to the expander power and the compressor power consumption. When the high-pressure storage pressure increases, the compression power consumption and expansion power also increase due to the increase in compression ratio and expansion ratio. However, the increase in expander power is less than the compressor power consumption, resulting in a downward trend in the round-trip efficiency. The increase in high-pressure storage pressure will reduce the volume of the high-pressure storage tank, and under the effect of the increase in expander power, the energy storage density of CCES gradually increases. When the high-pressure storage pressure is between 220bar-400bar, the energy storage density increases from 2.11kWh / m3 to 3.72kWh / m3.

[0094] The purchase cost of each component of the Allam-CCES system and the technical and economic analysis results of the system are as follows: Figure 8 and Table 3.

[0095] Table 3 Technical and economic analysis results

[0096]

[0097] according to Figure 8 It can be seen that among all the components, the purchase cost of the O2 compressor is the highest, reaching 89730.67k$. Among the components of the CCES part, the purchase costs of expander 1 and expander 2 are significantly higher than other components, which are 1910.52k$ and 1909.59k$ respectively. The data in Table 3 show that the total purchase cost and total investment cost of the Allam-CCES system are 120095.30k$ and 180142.90k$ respectively. The net present value of the system is 419927.80k$. The Allam-CCES coupling system still shows good economic benefits while achieving flexible power generation.

[0098] Compared with the traditional biomass gasification Allam cycle power generation system, the introduction of the CCES energy storage part of the integrated system has undoubtedly expanded the boundaries of LCA research, especially in the construction stage of CCES. This paper explores the carbon emissions of the entire life cycle of the integrated system charging and discharging process. The results are as follows Fig. 9 and Fig.10 .

[0099] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. An Allam cycle power generation system with integrated CO2 energy storage, characterized in that: The system includes: Allam cycle system, the Allam cycle system comprising a fuel compressor, a burner, a gas turbine, a heat exchanger, a flue gas cooler, a gas-liquid separator, a CO2 compressor, a splitter, a CO2 condenser A, a CO2 pump, an O2 compressor and a combiner A; A CO2 energy storage system, wherein the CO2 energy storage system comprises a combiner B, a CO2 condenser B, a low-pressure CO2 storage tank, an evaporator, a compressor, an intercooler, a high-pressure CO2 storage tank, a reheater, an expander and an H2O condenser; The coordinated work of CO2 cycle energy storage and power generation is achieved through the positional relationship and connection relationship of each component, including: The burner inlet of the Allam cycle system is connected to the cold stream outlet of the fuel compressor and the heat exchanger, and the burner outlet is connected to the gas turbine inlet; The hot stream inlet of the heat exchanger is connected to the outlet of the gas turbine, the cold stream inlet is connected to the outlet of the combiner A, and the cold stream outlet is connected to the inlet of the burner.

2. The Allam cycle power generation system with integrated CO2 energy storage according to claim 1 is characterized in that: The combiner B in the CO2 energy storage system is connected to the inlet of the CO2 condenser B, the outlet of the CO2 condenser B is connected to the inlet of the low-pressure CO2 storage tank, and the outlet of the low-pressure CO2 storage tank is connected to the inlet of the compressor through the evaporator.

3. The Allam cycle power generation system with integrated CO2 energy storage according to claim 1, characterized in that: The compressor outlet in the CO2 energy storage system is connected to the inlet of the high-pressure CO2 storage tank through an intercooler, the outlet of the high-pressure CO2 storage tank is connected to the inlet of the reheater, and the outlet of the reheater is connected to the inlet of the expander.

4. The Allam cycle power generation system with integrated CO2 energy storage according to claim 1, characterized in that: The H2O condenser is used to condense the high-temperature gas at the expander outlet and recover moisture, so as to achieve heat recovery and water resource utilization in the system.

5. The Allam cycle power generation system with integrated CO2 energy storage according to claim 1, characterized in that: The inlet position of the burner in the Allam cycle system is connected to the outlet position of the fuel compressor and the outlet position of the cold stream of the heat exchanger, and the outlet of the burner is connected to the inlet of the gas turbine to ensure that the fuel gas directly enters the gas turbine from the burner.

6. The Allam cycle power generation system with integrated CO2 energy storage according to claim 1, characterized in that: The hot stream inlet of the heat exchanger is connected to the outlet of the gas turbine, the cold stream inlet is connected to the outlet of the combiner A, and the cold stream outlet of the heat exchanger is connected to the inlet of the burner, ensuring that the mixed gas of CO2 and O2 enters the burner after heat exchange.

7. The Allam cycle power generation system with integrated CO2 energy storage according to claim 1, characterized in that: The inlet position of the gas-liquid separator is connected to the outlet position of the flue gas cooler, and the outlet position of the separator is connected to the inlet position of the CO2 compressor, which is used to compress the separated CO2 to a predetermined pressure, and the separated water is discharged from the system to achieve effective separation of water and CO2.

8. The Allam cycle power generation system with integrated CO2 energy storage according to claim 1, characterized in that: The inlet position of the combiner B in the CO2 energy storage system is connected to the outlet position of the expander and the outlet position of the splitter respectively, and the outlet position of the combiner B is connected to the inlet position of the CO2 condenser B, which is used to mix the expanded CO2 and the split CO2 and enter the condenser for condensation.

9. The Allam cycle power generation system with integrated CO2 energy storage according to claim 1, characterized in that: The outlet of the CO2 condenser B is connected to the inlet of the low-pressure CO2 storage tank, the outlet of the low-pressure CO2 storage tank is connected to the inlet of the evaporator, and the outlet of the evaporator is connected to the compressor and the intercooler in sequence to realize the condensation, low-pressure storage, reheating and compression processes of CO2; the high-pressure CO2 storage tank is installed between the intercooler and the reheater and connected by a pipeline; the outlet of the high-pressure CO2 storage tank is connected to the inlet of the cold stream of the reheater, and the outlet of the cold stream of the reheater is connected to the inlet of the expander, forming a working path for high-pressure storage and reheat expansion of CO2, which is used to realize the expansion and power generation of the stored high-pressure CO2.

10. A power generation method for an Allam cycle power generation system with integrated CO2 energy storage, characterized in that: The following steps are involved: S1: The fuel gas (natural gas, coal gasification gas or biomass gasification gas) is compressed by the fuel compressor and sent to the burner to mix with oxygen and burn to generate high-temperature flue gas; S2: Send the high-temperature flue gas into the gas turbine for expansion and power generation. The expanded flue gas flows through the heat exchanger to exchange heat with the mixed gas of CO2 and O2 from the CO2 compression pump and the O2 compressor; S3: Cool the flue gas to the gas-liquid separation temperature, separate the water from the CO2 through the gas-liquid separator, and the separated CO2 is compressed by the CO2 compressor and sent to the diverter. Part of the CO2 is used for power generation cycle, and the other part is sent to the CO2 energy storage system for storage.

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