An integrated co2 energy storage allam cycle power generation system and method

Abstract

The application 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 cycle 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 flow 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. The application provides an Allam cycle power generation system integrated with CO2 energy storage technology, the Allam cycle adopts transcritical CO2 as working fluid, and can directly provide circulating working medium for the energy storage system, thereby effectively saving cost. The system can solve the problems of low power generation efficiency and poor economy of the oxygen-enriched combustion power plant, and is conducive to realizing efficient carbon emission reduction of the power plant.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electric power, and in particular relates to an Allam cycle power generation system integrated with CO2 energy storage and a method thereof. BACKGROUND

[0002] In order to reduce carbon emissions, it is crucial 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 oxygen-enriched combustion power plants will cause additional power consumption and increase the cost of power plants. Therefore, exploring efficient and economical oxygen-enriched combustion power generation systems is of great significance for the large-scale popularization and application of CCUS technology.

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

[0004] Using renewable energy to generate electricity and promoting the low-carbon transformation of energy structure is also an important measure to cope with climate change. Due to the intermittent and unstable nature of renewable energy, the grid connection of large-scale renewable energy puts forward higher requirements for the flexibility of power plants. For fossil energy power generation systems, their peak shaving capacity should also be increased to meet the demand of the power grid and provide protection for the smooth transition of the energy structure, helping to achieve carbon emission reduction. The application of energy storage technology is an effective measure to balance power supply and demand. Integrating energy storage systems with oxygen-enriched combustion power generation systems is conducive to the safe and flexible operation of power plants.

[0005] Patents 202123269415.3 and 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 some 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 of charging and discharging. During the off-peak period, the CO2 is compressed using the power generated by the power plant, and the electric energy is stored in the form of pressure energy in the high-pressure CO2. During the peak period, the high-pressure CO2 is used to generate electricity through a turbine to release the stored electric energy. Compared with air, CO2 has better thermophysical properties and is easier to realize phase state conversion between gaseous, liquid and supercritical states, thereby reducing the cost of energy storage. In addition, the combination of CO2 energy storage technology and oxygen-enriched combustion power plant can directly provide part of the CO2 obtained by the carbon capture unit in the power plant to the energy storage system, without the need for additional preparation of 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 realize efficient and low-cost carbon emission reduction while ensuring the peak shaving capability of the power plant, an Allam cycle power generation system integrated with a CO2 energy storage system is constructed. Part of the CO2 separated from the flue gas after combustion in the Allam system can be used as the working fluid of the energy storage system, thereby increasing the utilization rate of CO2 and balancing the power load to form a stable power supply.

[0007] In view of the above analysis, the existing technical problems in the prior art are as follows:

[0008] The oxygen-enriched combustion power plant has the problems of low power generation efficiency and poor economy. SUMMARY

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

[0010] The present application is realized as follows: an Allam cycle power generation system integrated with a CO2 energy storage system, characterized in that the Allam cycle power generation system integrated with a CO2 energy storage system comprises an Allam cycle and a CO2 energy storage system. The Allam cycle 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; and the CO2 energy storage system comprises a flow 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 a H2O condenser.

[0011] Further, in the Allam cycle system, the inlet of the combustor is connected with the outlet of the fuel compressor and the outlet of the heat exchanger cold stream respectively, and the outlet of the combustor is connected with the inlet of the gas turbine; the hot stream inlet of the heat exchanger is connected with the gas turbine, and the cold stream inlet is connected with the outlet of the converging device A; the hot stream outlet of the heat exchanger is connected with the inlet of the flue gas condenser, and the cold stream outlet is connected with the inlet of the combustor; 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 for further cooling the flue gas, and the cooled flue gas is sent into the gas-liquid separator; the gas-liquid separator is used for separating water and CO2 in the flue gas, the separated water is discharged from the system, and the separated CO2 is sent into the CO2 compressor; the CO2 compressor is used for compressing the CO2 to the critical pressure, and the compressed CO2 is sent to the diverging device; the outlet of the diverging device is connected with the CO2 energy storage system and the CO2 condenser A respectively; the CO2 condenser A is used for cooling the CO2 to a liquid state, and the liquid CO2 is compressed to the combustion pressure by the CO2 compression pump; the inlet of the converging device A is connected with the outlet of the CO2 compression pump and the outlet of the O2 compressor respectively, and the outlet is connected with the cold stream inlet of the heat exchanger B; the O2 compressor is used for compressing the O2 to the combustion pressure.

[0012] Further, in the CO2 energy storage system, the inlet of the converging device B is connected with the outlet of the expander and the outlet of the diverging device respectively, and the outlet is connected with the CO2 condenser B; the CO2 condenser B, the low-pressure CO2 storage tank, the evaporator and the compressor are connected in sequence; the hot stream inlet of the intermediate cooler is connected with the outlet of the compressor, and the cold stream inlet is connected with the outlet of the cooler; the hot stream outlet of the intermediate cooler is connected with the high-pressure CO2 storage tank, and the cold stream outlet is connected with the hot stream inlet of the reheater; the hot stream inlet of the reheater is connected with the cold stream outlet of the intermediate cooler, and the cold stream inlet is connected with the outlet of the high-pressure CO2 storage tank; the hot stream outlet of the reheater is connected with the inlet of the cooler, and the cold stream outlet is connected with the outlet of the expander.

[0013] Further, the compressor is used for compressing the CO2 to the high-pressure storage pressure, the intermediate cooler is used for cooling the CO2 at the outlet of the compressor by using water; the expander is used for CO2 expansion power generation, the reheater is used for increasing the temperature of the CO2 at the inlet of the expander, so as to improve the power generation efficiency; the cooler is used for further cooling the heat exchange medium at the outlet of the reheater, and then the heat exchange medium is sent into the intermediate cooler for heat exchange.

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

[0015] When the electricity load is at a low point, the CO2 energy storage system starts to charge, and the liquid CO2 in the low-pressure CO2 storage tank is first heated to a gaseous state by a preheater, then sequentially passes through a compressor and an intermediate cooler, at which time the CO2 is a high-pressure liquid, and is stored in the high-pressure CO2 storage tank, and the electricity required by the compressor is provided by the gas turbine in the Allam cycle;

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

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

[0018] Further, the CO2 energy storage system can adopt double-stage compression and double-stage expansion, or multi-stage compression and multi-stage expansion, and an intermediate cooler is arranged at the outlet of each compressor, and a reheater is arranged at the inlet of each expander.

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

[0020] Further, the heat exchange medium in the CO2 energy storage system can be selected from water, heat-conducting oil, and salt solution.

[0021] In combination with the above technical solutions and the technical problems solved, the technical solutions to be protected by the present application have the following advantages and positive effects:

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

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

[0024] The application couples a CO2 energy storage system with a biomass gasification Allam cycle, utilizes the characteristics of the Allam cycle that trans-critical CO2 is used as a working medium, solves the working medium source problem of the energy storage system, improves the utilization rate of CO2, and increases the stability of the power generation system.

[0025] The application uses excess electricity as energy input of the energy storage unit during the low electricity consumption valley, and releases electric energy during the electricity consumption peak, so as to store excess electricity, relieve the power supply pressure during the peak period, and ensure the stable operation of the power plant.

[0026] The application adopts compressed CO2 as the working fluid of the energy storage unit, is easy to realize phase change, has compact system structure, and reduces investment cost.

[0027] The product of the application further includes liquid CO2 in addition to electricity, improves the economic benefit and environmental friendliness of the power plant, and is beneficial to the realization of the double-carbon target.

[0028] Secondly, the compressed CO2 carbon energy storage system provided by the application has the advantages of large energy storage density, low economic cost, long service life, negative carbon emission, etc. as a new type of compressed gas energy storage technology. Secondly, the system is not limited by geographical conditions, the working medium is easy to obtain, the working condition is stable, the charging and discharging states can be freely switched, 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 biomass power generation and other new energy sources to effectively overcome the power generation volatility and intermittency, and can be matched with a generator set for use, as power compensation when the generator set is flexibly adjusted for peak power generation, greatly improving the peak regulation capacity and energy comprehensive utilization efficiency of the generator set. At the same time, the system can also be combined with a carbon dioxide capture and storage system to realize integrated carbon dioxide recycling and utilization, and has a broad application prospect. Therefore, the research and application of the compressed carbon dioxide energy storage coupling Allam cycle system not only fills the research gap in this field at home and abroad, but also provides an important solution for the future renewable energy-based energy system and multi-energy collaborative complementary network.

[0029] The technical scheme of the application solves the technical problem that people have been eager to solve but have always failed to succeed: the low-pressure side CO2 liquefaction problem: in the traditional compressed carbon dioxide energy storage system, the cold quantity required for the liquefaction of the low-pressure side CO2 is at subzero temperature, the heat exchange condition is harsh, and it is difficult to realize. The system adjusts the outlet pressure of the low-pressure side CO2 by using a throttle valve, further reduces the CO2 temperature, and recycles the cold quantity for the liquefaction of the CO2 at the outlet of the expander, effectively solving the problem of uneven energy matching in the cold storage and heat exchange process

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

[0031] Efficient absorption and utilization of compression heat: The system arranges multiple heat storage units in series to absorb CO2 compression heat, using water as the heat storage medium. By taking advantage of the low cost of water, the system realizes efficient absorption and utilization of compression heat, improving system energy utilization rate.

[0032] Third, the existing gas turbine cycle system has the problems of low efficiency and high CO2 emission, and the waste heat utilization rate is insufficient, and the environmental protection is poor. To solve this problem, the Allam cycle system innovatively uses CO2 as the main working fluid, improves the system efficiency through the thermodynamic properties under supercritical conditions, and realizes the capture and recycling of CO2. The system adopts a fully enclosed cycle structure, through the close coupling of the burner, gas turbine and heat exchanger, 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 has low efficiency in dealing with large-scale energy storage and conversion, and 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 realizes efficient energy storage and flexible deployment 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 system stability, and significantly improve the energy conversion efficiency through the integrated design of energy storage and power generation.

[0034] Traditional heat exchangers have large heat loss under high temperature and high pressure conditions, and the equipment volume is large and the pressure resistance is insufficient, which cannot meet the needs of efficient circulation. To solve these problems, the heat exchanger in the 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 volume and material cost of the equipment, and through the use of high-temperature and high-pressure resistant materials, the heat exchanger can operate stably in the supercritical CO2 environment for a long time, laying a foundation for the improvement of the overall efficiency of the system.

[0035] The low gas-liquid separation efficiency and large energy loss restrict the performance of the traditional power generation system. Through optimizing the separation path and fluid control design, the gas-liquid separator realizes high-purity and efficient separation of CO2, meeting the pure demand of the system for working fluid. In addition, the expander fully utilizes the expansion process of high-pressure gas to recover energy, efficiently converts pressure energy into mechanical energy, and combines with the heat management strategy to improve the heat energy recovery efficiency. These improvements further improve the energy utilization rate and operation reliability of the system, providing support for new power generation and energy storage integrated technology. BRIEF DESCRIPTION OF DRAWINGS

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

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

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

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

[0040] Figure 5 is a loss distribution diagram of an Allam-CCES system provided by an embodiment of the present application;

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

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

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

[0044] Figure 9 is a disassembled diagram of GWP results of charging process of an integrated system provided by an embodiment of the present application;

[0045] Figure 10 is a disassembled diagram of GWP results of discharging process of an integrated system provided by an embodiment of the present application;

[0046] ​In the figure: 1, fuel compressor; 2, combustor; 3, gas turbine; 4, heat exchanger; 5, flue gas cooler; 6, gas-liquid separator; 7, CO2 compressor; 8, flow divider; 9, CO2 condenser A; 10, CO2 pump; 11, O2 compressor; 12, flow combiner A; 13, flow combiner B; 14, CO2 condenser B; 15, low-pressure CO2 storage tank; 16, evaporator; 17, compressor; 18, intercooler; 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, tertiary compressor; 31, tertiary intercooler; 32, tertiary reheater; 33, tertiary expander; 34, cooler C. DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0048] As Figure 1As shown, the embodiment of the present application provides an integrated CO2 energy storage Allam cycle power generation system, comprising: an Allam cycle, a CO2 energy storage system. The Allam cycle system specifically comprises 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 flow divider 8, a CO2 condenser A 9, a CO2 pump 10, an O2 compressor 11 and a flow combiner A 12; the inlet of the burner 2 is connected with the outlet of the fuel compressor 1 and the cold flow outlet of the heat exchanger 4 respectively, and the outlet of the burner 2 is connected with the inlet of the gas turbine 3; the hot flow inlet of the heat exchanger 4 is connected with the gas turbine 3, and the cold flow inlet is connected with the outlet of the flow combiner A 12; the hot flow outlet of the heat exchanger 4 is connected with the inlet of the flue gas cooler 5, and the cold flow outlet is connected with 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 flow of CO2 and O2; the flue gas cooler 5 is used for further cooling the flue gas, and the cooled flue gas is sent into the gas-liquid separator 6; the gas-liquid separator 6 is used for separating water and CO2 in the flue gas, the separated water is discharged from the system, and the separated CO2 is sent into the CO2 compressor 7; the CO2 compressor 7 is used for compressing the CO2 to near the critical pressure, and the compressed CO2 is sent to the flow divider 8; the outlet of the flow divider 8 is connected with the CO2 energy storage system and the CO2 condenser A 9 respectively; the CO2 condenser A 9 is used for cooling the CO2 to liquid state, and the liquid CO2 is compressed to the combustion pressure by the CO2 compression pump 10; the inlet of the flow combiner A 12 is connected with the outlet of the CO2 compression pump 10 and the outlet of the O2 compressor 11 respectively, and the outlet is connected with the cold flow inlet of the heat exchanger B 4; the O2 compressor 11 is used for compressing the O2 to the combustion pressure;

[0049] The CO2 energy storage system comprises a flow combiner B 13, a CO2 condenser B 14, a low-pressure CO2 storage tank 15, an evaporator 16, a compressor 17, an intermediate cooler 18, a high-pressure CO2 storage tank 19, a reheater 20, an expander 21 and an H2O condenser 22; the inlet of the flow combiner B 13 is connected with the outlet of the expander 21 and the outlet of the flow divider 8 respectively, and the outlet is connected with the CO2 condenser B 14; the CO2 condenser B 14, the low-pressure CO2 storage tank 15, the evaporator 16 and the compressor 17 are connected in sequence; the hot flow inlet of the intermediate cooler 18 is connected with the outlet of the compressor 17, and the cold flow inlet is connected with the outlet of the cooler 22; the hot flow outlet of the intermediate cooler 18 is connected with the high-pressure CO2 storage tank 19, and the cold flow outlet is connected with the hot flow inlet of the reheater 20; the hot flow inlet of the reheater 20 is connected with the cold flow outlet of the intermediate cooler 18, and the cold flow inlet is connected with the outlet of the high-pressure CO2 storage tank 19; the hot flow outlet of the reheater 20 is connected with the inlet of the cooler 22, and the cold flow outlet is connected with the outlet of the expander 21.

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

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

[0052] When the electricity load is at the trough, the CO2 energy storage system starts to charge, the liquid CO2 in the low-pressure CO2 storage tank 15 is first heated to gas by the preheater 16, and then passes through the compressor 17 and the intercooler 18 in turn, at this time the CO2 is high-pressure liquid, enters the high-pressure CO2 storage tank 19 for storage, and 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 the 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, releases the stored electric energy, the outlet CO2 of the expander 21 is mixed with part of the separated CO2 in the Allam cycle, and the mixed CO2 is condensed into liquid by the CO2 condenser B (14), and the liquid CO2 is stored in the low-pressure CO2 storage tank 15.

[0054] The fluid at the inlet of the fuel compressor includes natural gas, coal gasification gas, biomass gasification gas and other gaseous fuels.

[0055] The CO2 energy storage system can adopt double-stage compression and double-stage expansion, or multi-stage compression and multi-stage expansion, and an intercooler is arranged at the outlet of each compressor, and a reheater is arranged at the inlet of each expander.

[0056] The CO2 energy storage system is provided with a compressor after the combiner B, which further compresses the CO2 to a supercritical state, and the energy storage unit uses supercritical CO2 as working fluid.

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

[0058] The integrated CO2 energy storage Allam cycle power generation system of the present application realizes efficient utilization and storage of energy by combining a CO2 energy storage system with an Allam cycle. The Allam cycle part generates high-temperature and high-pressure flue gas by using components such as a fuel compressor, a combustor and a gas turbine. 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. The CO2 circulates in the system, is compressed, split, cooled to form liquid, and is pressurized by a CO2 compressor to the pressure required for combustion by a CO2 pump to be sent back to the combustor to participate in the cycle.

[0059] The design of the CO2 energy storage system allows energy to be stored during the low valley of power load and released during the peak of power demand. During the low valley, the CO2 energy storage system warms the liquid CO2 in the low-pressure CO2 storage tank to gas by a preheater, and then compresses and intercools the gas to form high-pressure liquid CO2 and store it in a high-pressure CO2 storage tank. The energy required for compression is provided by the gas turbine in the Allam cycle. During the peak, the CO2 energy storage system releases CO2 from the high-pressure CO2 storage tank, heats it by a reheater, expands it in an expander to generate electricity, and the expanded CO2 is mixed with part of the CO2 separated from the Allam cycle to condense and return to the low-pressure storage tank.

[0060] The system realizes efficient energy storage and power generation of CO2 circulation through position and connection relationship. The components such as the compressor, the expander, the condenser and the reheater work cooperatively to dynamically adjust the storage and release process of CO2 under different load conditions. The energy conversion efficiency of CO2 in the compression and expansion process is high, and the energy loss of the traditional energy storage method is reduced.

[0061] Finally, the integrated system has recyclable CO2 energy storage and power generation capacity, reduces the emission of CO2 in the traditional power generation method, and improves the cleanliness and efficiency of the power generation system.

[0062] Embodiment one:

[0063] The present embodiment provides a biomass gasification Allam cycle integrated CO2 energy storage system, as shown in Figure 2 The biomass gasification Allam cycle integrated CO2 energy storage system includes a biomass gasifier 23, a syngas cooler 24, a fuel compressor 1, a combustor 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 A 9, a CO2 pump 10, an O2 compressor 11, a combiner A 12, a combiner B 13, a CO2 condenser B 14, a low-pressure CO2 storage tank 15, a preheater 16, a compressor 17, an intercooler 18, a high-pressure CO2 storage tank 19, a reheater 20, an expander 21 and a cooler 22.

[0064] The outlet of the biomass gasifier 23 is connected to the hot stream inlet of the syngas cooler 24, the biomass gasifier 23 is used for the reaction of biomass raw material and gasification agent to generate gasification syngas, the syngas cooler 24 is used for heat exchange between the high-temperature syngas at the outlet of the biomass gasifier 23 and the gasification agent, the gasification agent is heated to the gasification temperature, and the cooled syngas is sent to the fuel compressor 1, and the fuel compressor 1 is used to compress the biomass gasification syngas to the combustion pressure.

[0065] The inlet of the combustor 2 is connected to the cold stream outlet of the heat exchanger 4 and the outlet of the fuel compressor 1 respectively; the combustor 2 is used for the combustion of the biomass gasification syngas, and the flue gas after combustion is sent to the gas turbine 3 for expansion 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 for separating water and CO2 in the flue gas, the separated water is discharged from the system, and the remaining CO2 is sent to the CO2 compressor 7; the CO2 compressor 7 is used to compress the CO2 to above the critical pressure, and the compressed CO2 is sent to the flow divider 8; the flow divider 8 is used to divide the CO2 into two streams, one of which is sent to the CO2 energy storage system as a working medium, and the other of which 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 inlets of the flow combiner A12 are respectively connected to the outlets of the CO2 pump 10 and the O2 compressor 11; the O2 compressor 11 is used to compress the O2 to the combustion pressure;

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

[0067] When charging, part of the CO2 in the low-pressure CO2 storage tank 15 is captured and stored, 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 intermediate cooler 18; the first intermediate cooler 18 is used to cool the compressed CO2, and then the high-pressure CO2 is sent to the high-pressure CO2 storage tank 19 for storage.

[0068] When discharging, 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 power; the outlet of the expander 21 is connected to the flow combiner B13.

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

[0070] Example Two:

[0071] This example provides an Allam cycle integrated with a two-stage compression turbine CO2 energy storage system as shown in FIG. 2. Figure 3 The difference between the energy storage system of Example One and Example Two is that the CO2 energy storage system of Example Two uses two-stage compression and two-stage expansion.

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

[0073] During discharging, the CO2 in high-pressure CO2 storage tank 19 is first heated by two-stage re-heater 27, and then enters two-stage expander 28 to expand and generate electricity; the outlet of two-stage expander 28 is connected to the cold stream inlet of re-heater 20; said re-heater 20 is used to heat the expanded CO2 and send it to expander 25 for further expansion to generate electricity.

[0074] Cooler 22 is connected to the hot stream outlet of re-heater 20 and to the cold stream inlet of intercooler 18; cooler B29 is connected to the hot stream outlet of two-stage re-heater 27 and to the cold stream inlet of two-stage intercooler 26; said coolers 22 and B29 are used to cool the heat transfer medium.

[0075] Example Three:

[0076] This example provides an Allam cycle integrated with a three-stage compression turbine CO2 energy storage system as shown in FIG. 3. Figure 4 The difference between Example One and Example Three is that the CO2 energy storage system uses three-stage compression and three-stage expansion.

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

[0078] During discharging, the CO2 in the high-pressure CO2 tank is expanded by three stages, and the stored pressure energy is converted into electrical energy; in order to ensure the expansion power generation efficiency, the CO2 is first heated by the reheater before entering the expander; in the reheater, the CO2 exchanges heat with the circulating heat exchange medium in the energy storage system, and absorbs 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 turn, is mixed with the CO2 in the Allam cycle, is liquefied by the CO2 condenser B14, and enters the low-pressure CO2 tank 15 for storage.

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

[0080] The specific application field of the present application mainly focuses on energy conversion and energy storage technology. The system can improve the performance of the compressed carbon dioxide energy storage system, realize the cascade utilization of energy through the coupling with the biomass gasification Allam cycle system, and improve the system efficiency. The specific applications include:

[0081] Electric power energy storage: the system can be used as a form of electric power energy storage, especially in occasions requiring large-scale energy storage solutions, such as grid load balancing and integration of renewable energy.

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

[0083] CO2 capture and utilization: the system deeply couples the CO2 capture of the Allam cycle system, and uses the captured carbon dioxide for the energy storage system. The integrated system has recyclable CO2 energy storage and power generation capacity, reduces the CO2 emission in the traditional power generation mode, and improves the cleanliness and efficiency of the power generation system.

[0084] The present application 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] The net power generation of the Allam-CCES system is 74.95 MW and the power generation efficiency is 36.43% during charging process. During discharging process, the net power generation and the power generation efficiency of the system are 81.17 MW and 39.45%, respectively. The results show that the coupling of the CCES system can improve the flexibility of the biomass gasification Allam cycle power generation and has a certain peak shaving ability. The round-trip efficiency of the CCES in the coupling system is 62.04%

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

[0087]

[0088] The energy analysis results of each component of the Allam-CCES system and the system loss distribution are shown in Table 2 and Figure 5 Table 3, respectively. The total loss of the system is 254.86 MW, of which the loss rate of the CCES system part is 15.6%, and the rest loss comes from the components of the Allam cycle. Among all the components of the system, the loss of the gasifier accounts for the largest proportion, which is 21.8%, followed by the condenser 1, the cooler 2 and the combustor, which account for 17.8%, 17.7% and 17.4% of the total loss, respectively. Table 2 Energy analysis results of the Allam-CCES system

[0089] Table 3 Loss distribution of the Allam-CCES system

[0090]

[0091]

[0092] The variation trends of the round-trip efficiency and the energy storage density of the Allam-CCES system with the low-pressure storage pressure in the range of 72.3-78.0 bar are shown in Figure 6 . Due to the sudden change of the energy consumption of the compressor 1 caused by the phase transition of CO2 with the increase of the pressure, the round-trip efficiency of the CCES in the coupling system also suddenly decreases between the low-pressure storage pressures of 74.5-75.0 bar, and reaches the maximum value of 90.71% when the low-pressure storage pressure is 74.5 bar. With the increase of the low-pressure storage pressure from 72.3 bar to 78.0 bar, the energy storage density increases from 2.72 kWh / m3 to 2.91 kWh / m3, and the growth rate gradually slows down. This trend is the same as the variation trend of the energy storage density of the CCES system alone, which is the result of the decrease of the expander power being less than the decrease of the low-pressure storage tank volume.

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

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

[0095] Table 3 Results of technical and economic analysis

[0096]

[0097] According to Figure 8 , among all the components, the purchase cost of the O2 compressor is the highest, reaching 89730.67 k$. Among the components of the CCES part, the purchase cost of the expander 1 and the expander 2 is significantly higher than that of other components, being 1910.52 k$ and 1909.59 k$, respectively. The data in Table 3 show that the total purchase cost and the total investment cost of the Allam-CCES system are 120095.30 k$ and 180142.90 k$, respectively. The net present value of the system is 419927.80 k$, and the Allam-CCES coupled 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 integrated system CCES energy storage part undoubtedly expands the boundary of the LCA study, especially in the construction stage of the CCES. The present invention explores the full life cycle carbon emissions of the integrated system charging and discharging process, and the results are shown in Figure 9 and Figure 10 .

[0099] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement within the technical range disclosed by the present application and within the spirit and principle of the present application should be covered within the protection scope of the present application.

Claims

1. An integrated CO2 storage energy Allam cycle power generation system, characterized by, The system comprises: an Allam cycle system comprising 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 and a flow combiner A connected in sequence; the Allam cycle system further comprises an O2 compressor, and an inlet of the flow combiner A is connected to outlets of the CO2 pump and the O2 compressor respectively; a CO2 energy storage system comprising a flow 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 a cooler; the flow combiner B in the CO2 energy storage system is connected to an inlet of the CO2 condenser B, an outlet of the CO2 condenser B is connected to an inlet of the low-pressure CO2 storage tank, and an outlet of the low-pressure CO2 storage tank is connected to an inlet of the compressor through the evaporator; an outlet position of the flow combiner B in the CO2 energy storage system is connected to an outlet position of the expander and an outlet position of the flow divider respectively, and an inlet position of the flow combiner B is connected to an inlet position of the CO2 condenser B, for mixing the expanded CO2 and the divided CO2 and entering the condenser for condensation; a hot stream inlet of the intercooler is connected to an outlet of the compressor, and a cold stream inlet is connected to an outlet of the cooler; a hot stream outlet of the intercooler is connected to the high-pressure CO2 storage tank, and a cold stream outlet is connected to a hot stream inlet of the reheater; a hot stream inlet of the reheater is connected to a cold stream outlet of the intercooler, and a cold stream inlet is connected to an outlet of the high-pressure CO2 storage tank; a hot stream outlet of the reheater is connected to an inlet of the cooler, and a cold stream outlet is connected to an inlet of the expander; wherein: an inlet of the combustor of the Allam cycle system is connected to a cold stream outlet of the fuel compressor and the heat exchanger, and an outlet of the combustor is connected to an inlet of the gas turbine; a hot stream inlet of the heat exchanger is connected to an outlet of the gas turbine, a cold stream inlet is connected to an outlet of the flow combiner A, and a cold stream outlet is connected to an inlet of the combustor.

2. The integrated CO2 storage energy Allam cycle power generation system of claim 1, wherein, The cooler is used for further cooling the heat exchange medium at the outlet of the reheater and then sending it to the intercooler for heat exchange.

3. The integrated CO2-energystored Allam cycle power generation system of claim 1, wherein, An outlet position of the gas-liquid separator is connected to an outlet position of the flue gas cooler, and an inlet position of the CO2 compressor is connected to an outlet position of the gas-liquid separator, for compressing the separated CO2 to a predetermined pressure, and the separated water is discharged from the system, so as to realize effective separation of water and CO2.

4. The integrated CO2-energystored Allam cycle power generation system of claim 1, wherein, An outlet position of the CO2 condenser B is connected to an inlet of the low-pressure CO2 storage tank, an outlet of the low-pressure CO2 storage tank is connected to an inlet of the evaporator, and an outlet of the evaporator is connected to the compressor and the intercooler in sequence, so as to realize condensation, low-pressure storage and reheating and compression processes of CO2; the high-pressure CO2 storage tank is installed between the intercooler and the reheater and is connected through a pipeline; an outlet position of the high-pressure CO2 storage tank is connected to an inlet of a cold stream of the reheater, and an outlet of the cold stream of the reheater is connected to an inlet of the expander, so as to form a working path of high-pressure storage and reheating expansion of CO2, and to realize expansion power generation of the stored high-pressure CO2.

5. A method of power generation for the integrated CO2 energy storage Allam cycle power generation system of claim 1, characterized in that, comprising the following steps: S1: the fuel gas is compressed by a fuel compressor and then sent to a combustor to be mixed with oxygen and combusted to generate high-temperature flue gas; S2: the high-temperature flue gas is sent to a gas turbine to be expanded to generate power, and the expanded flue gas flows through a heat exchanger to exchange heat with CO2 and O2 mixed gas from a CO2 compression pump and an O2 compressor; S3: the flue gas is cooled to a gas-liquid separation temperature, and water and CO2 are separated by a gas-liquid separator, the separated CO2 is compressed by a CO2 compressor and sent to a flow divider, part of the CO2 is used for power generation cycle, and the other part is sent to a CO2 energy storage system for storage.

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