Power generation system and method based on carbonation calcination cycle coupling thermochemical energy storage

Abstract

The invention provides a power generation system and method based on carbonation calcination cycle coupling thermochemical energy storage. The power generation system comprises a carbonate calcination reactor, a COturbine power generation unit, a carbonation reactor, a thermochemical energy storage unit, a heat exchange network and a control system. According to the invention, industrial waste heat or renewable energy electric power is utilized to drive carbonate calcination to generate high-temperature COs to push the turbine to generate power; meanwhile, a calcined product CaO / MgO enters a carbonation reactor to absorb COO in smoke or the atmosphere, carbon sequestration circulation is completed, high-temperature heat needed by calcination is supplied by high-grade heat energy stored by a thermochemical energy storage unit in the charging stage, and the heat energy comes from surplus electric power or system power generation tail gas waste heat; the thermochemical energy storage unit releases heat to drive calcination in the discharging stage, and power grid peak regulation and energy time shifting are achieved. The problems of intermittency and carbon emission of traditional thermal power / wind and light power generation are solved, and integration of efficient, low-carbon and schedulable power output and carbon capture is achieved.

Description

Technical Field

[0001] The present invention relates to the field of energy technology, and in particular to a power generation system and method based on carbonation-calcination cycle coupled with thermochemical energy storage. Background Art

[0002] Traditional thermal power generation relies primarily on burning fossil fuels to generate energy. This approach not only has limited efficiency but also emits large amounts of carbon dioxide, severely impacting the environment. While renewable energy sources such as wind power and photovoltaics are clean, they suffer from intermittent and volatile power. To ensure a stable power supply, supporting energy storage facilities are essential.

[0003] The introduction of calcium cycle (CaL) technology offers a new approach to capturing carbon dioxide from coal-fired power plants. However, this technology consumes a lot of energy during the calcination process and requires external fuel for heating, which greatly reduces the efficiency of the system. Thermochemical energy storage relies on reversible reactions to store and release heat, and has the advantages of high energy storage density, long-term storage, and a wide temperature range. Currently, existing technologies have not effectively solved the problem of synergistically optimizing energy storage, power generation, and carbon capture, nor have they been able to effectively utilize surplus electricity to drive energy storage and carbon capture. Summary of the Invention

[0004] The purpose of the present invention is to provide a power generation system and method based on a carbonation-calcination cycle coupled with thermochemical energy storage, overcome the shortcomings of the existing technology, and provide an integrated system and method that can simultaneously achieve efficient power generation, deep carbon capture, large-scale energy storage and flexible grid regulation.

[0005] To achieve the above object, the present invention provides the following technical solutions: A power generation system based on carbonation-calcination cycle coupled with thermochemical energy storage, comprising: Calcination reactor: used for decomposition reaction of carbonate minerals at high temperature: CaCO3->CaO+CO2-ΔH; CO2 turbine power generation unit: connected to the outlet of the calcination reactor, receives high-temperature and high-pressure CO2 gas to drive the turbine to generate electricity, followed by a generator and a compressor (regenerative cycle is optional); Carbonation reactor: Receives part of the CO2 (or external flue gas / air) from the turbine power generation unit and CaO particles produced by calcination, and undergoes a carbonization reaction: CaO+CO2->CaCO3+ΔH; Thermochemical energy storage unit: contains MO red +1 / 2O2->MO ox +ΔH (exothermic) and MO ox ->MO red+1 / 2O2-ΔH (endothermic) reversible redox reaction materials (such as Co3O4 / CoO, Mn2O3 / Mn3O4, etc.); Key coupling components: The first heat exchanger: transfers the high-temperature heat energy released by the thermochemical energy storage unit in the "discharge mode" to the calcination reactor to drive the decomposition of carbonates; The second heat exchanger and controllable valve transfers the high-temperature CO2 waste heat generated by the calcination reactor or the waste heat from the system's power generation exhaust to the thermochemical energy storage unit for endothermic reaction (reduction decomposition) in "charging mode"; or inputs the electrical heating energy generated by surplus electricity to the unit; Heat carrier circuit: Molten salt or inert gas can be selected to circulate heat between the first heat exchanger, the second heat exchanger and the thermochemical energy storage unit; Solid material circulation device: used to transport the CaCO3 generated in the carbonation reactor back to the calcination reactor to complete the cycle; CO2 diversion and control valve: controls the ratio of CO2 flowing to the carbonation reactor and direct capture / storage; Control system: Based on grid demand signals, energy storage status, and energy input, the system operation mode (power generation priority, energy storage priority, carbon capture priority) is adjusted in real time.

[0006] The power generation and thermochemical energy storage method of the power generation system based on the carbonation calcination cycle coupled with thermochemical energy storage includes the following modes: Power generation and energy storage coupling mode (normal / valley period): When the control system determines that it needs to generate electricity and / or utilize cheap electricity (valley electricity / surplus wind and photovoltaic power), it starts "charging" the energy storage unit: using the electric heater (or system waste heat) to heat the heat carrier medium, driving the thermochemical energy storage material to undergo an endothermic reduction reaction (storing energy); The high-grade heat energy stored in the thermochemical material is transferred to the calcination reactor through the first heat exchanger to heat CaCO3 to the decomposition temperature, generating high-temperature CO2 and CaO; High-temperature and high-pressure CO2 drives the turbine to drive the generator to generate electricity. After treatment, part of the tail gas enters the carbonation reactor and part can be captured; The generated CaO is sent to the carbonation reactor to absorb CO2 from flue gas or air to generate CaCO3, which is then sent back to the calcination reactor by the solid material circulation device; Peak load regulation and energy release mode (during peak power period / when wind and solar power are insufficient): The control system receives a signal from the power grid demanding peak load and increases the intensity of the calcination; The thermochemical energy storage unit enters the "discharge mode": external air is introduced, triggering the exothermic oxidation reaction of the material, releasing a large amount of high-temperature heat; The released heat is quickly transferred to the calcination reactor via the first heat exchanger, increasing the reaction rate and CO2 production, thereby significantly improving the turbine power output and responding to the peak load demand of the power grid.

[0007] Compared with the prior art, the present invention has the following beneficial effects: Low-carbon and high-efficiency power generation: The combustion process is eliminated (or minimized), the core energy input of the system is industrial waste heat or renewable energy electricity, and net CO2 emissions are significantly reduced or even negative (combined with air capture); Deep carbon capture: The carbonation process directly captures CO2 to form stable carbonates, with a capture efficiency of over 90%, and is an inherent part of the system; Large-scale, long-term energy storage: The energy density of thermochemical energy storage far exceeds that of traditional thermal storage (molten salt) and lithium batteries, and it can be stored for a long time without loss, and its capacity is easily expandable; Flexible adjustment capability: Utilizing the energy storage unit to quickly release heat energy to drive calcination, the power generation capacity can be increased several times within minutes (e.g., from 30% load to 100%+), supporting grid stability. Reduce calcination energy consumption: Abandon external fuels and rely on renewable electricity and energy storage for energy supply, improving the overall efficiency of the system; Resource recycling: CaO / CaCO3 is closed-circulated within the system, and no solid waste is generated. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram of the device of the present invention; Figure 2 This is a schematic diagram of the energy release (discharge) process of the present invention; Figure 3 Schematic diagram of control signal flow in the present invention.

[0009] In the figure: 1. Calcination reactor; 2. CO2 turbine power generation unit; 3. Carbonation reactor; 4. Thermochemical energy storage unit; 5. First heat exchanger; 6. Second heat exchanger; 7. Heat carrier loop; 8. Solid material circulation device; 9. CO2 diversion and control valve; 10. Control system. DETAILED DESCRIPTION

[0010] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0011] Example 1: The present invention is a clean power generation system and working method that combines chemical cycle power generation, carbon capture and thermochemical energy storage, and is particularly suitable for using renewable energy or industrial waste heat for efficient and low-carbon power generation and grid peak regulation.

[0012] In this embodiment, in response to the demand for industrial waste heat utilization and renewable energy peak regulation, an integrated power generation and carbon storage system is constructed based on the CaCO3 / CaO cycle and Co3O4 / CoO composite material as the thermochemical energy storage medium.

[0013] In this power generation system, the calcination reactor 1 decomposes carbonate at high temperature to generate CaO and CO2 gas. The CO2 gas is passed into the CO2 turbine power generation unit 2 from the CO2 outlet of the calcination reactor 1. The exhaust port of the unit is connected to the inlet of the carbonation reactor 3. At the same time, the CaO outlet of the calcination reactor 1 is also connected to the inlet of the carbonation reactor 3, so that CaO and CO2 undergo a carbonation reaction in the carbonation reactor 3 to generate CaCO3. The generated CaCO3 is transported from the CaCO3 outlet of the carbonation reactor 3 to the CaCO3 inlet of the calcination reactor 1 by the solid material circulation device 8 to complete the circulation.

[0014] A first heat exchanger 5 is arranged between the thermochemical energy storage unit 4 and the calcination reactor 1, which is used to transfer the heat released by the thermochemical energy storage unit 4 in the energy release mode to the calcination reactor 1. The second heat exchanger 6 is arranged between the CO2 turbine power generation unit 2 or the system exhaust gas waste heat source and the thermochemical energy storage unit 4, which is used to transfer the waste heat or heat generated by the electric heating device to the thermochemical energy storage unit 4. The heat carrier loop 7 circulates through the first heat exchanger 5, the second heat exchanger 6 and the thermochemical energy storage unit 4 to transfer heat. The CO2 diversion device is arranged downstream of the exhaust port of the CO2 turbine power generation unit 2, which is used to adjust the flow of CO2 flowing to the carbonation reactor 3 and the captured and stored CO2. The control system 10 regulates the system's operating mode and energy distribution according to the external demand signal, and the thermochemical energy storage unit 4 contains materials such as Co3O4 / CoO that can undergo reversible redox reactions.

[0015] The core material of the system uses Co3O4 / CoO composite material as the thermochemical energy storage medium. The material has a specific capacitance of 276.1F / g at a scanning rate of 5MV / s. After 10,000 cycles, the capacitance retention rate is still 82.37%, and it can withstand high temperatures of 1100°C.

[0016] The charging / exothermic temperature range of the reversible redox reaction of the Co3O4 / CoO composite material is 900~1000℃, which is highly compatible with the operating temperature of the calcination reactor of 1850~950℃. The carbonation reactor 3 has a maximum volume of 80m³ and a diameter of 6500mm.

[0017] The control system 10 can dynamically switch the operating mode according to the grid load: during the off-peak period, the surplus electricity is used to "charge" the energy storage unit, and during the peak period, "discharge" is triggered to increase the CO2 production of the calcination reactor 1. By adjusting the CO2 diverter valve and the solid material circulation rate, the coordinated optimization of power generation power, energy storage status and carbon capture efficiency is achieved.

[0018] When the power grid needs to be peak-shaving, the main controller starts the energy release instruction, and CaO and Co2 are delivered to the carbonation reactor 3 in proportion. The pressure valve controls the operating pressure of the carbonation reactor 3 to be 0.5~2MPa, and the reaction temperature is maintained at 700~750℃ through the temperature controller to optimize the reaction rate.

[0019] The released heat heats the critical Co2 through the heat exchanger, driving the CO2 turbine power generation unit 2 to generate electricity. The power generation power is dynamically adjusted by the load demand, for example, by frequency conversion to control the expander speed.

[0020] The inlet CO2 volume flow rate of carbonation reactor 3 is 14068.7m³ / h, corresponding to a space velocity of 3500h⁻¹, and the heat of carbonation reaction is about 180 kJ / mol CO2, when the system heat load is 10MW, the CO2 molar flow rate can be calculated as 200000 by the following formula mol / h (about 4.48 tons / hour); CO2 flow calculation: The heat transfer area is determined to be 2000m² based on the heat load method (heat transfer coefficient k=500 W / m²・K , temperature difference ΔT=10℃), heat transfer area ( A )calculate: The high-temperature CO2 (pressure 2~8MPa) generated by the calcination reactor 1 drives the CO2 turbine power generation unit 2 to generate a typical power of 10MW. The accompanying thermochemical energy storage unit can achieve an energy storage time equivalent to 6 hours and a carbon capture efficiency of more than 90%.

[0021] Example 2: It is basically the same as Example 1, with the following slight differences: This embodiment introduces an oxygen-enriched calcination process or a bimetallic oxide energy storage material (such as a material containing Mn and Fe) on the basis of embodiment 1 to improve the system dynamics.

[0022] Oxygen-rich gas can be introduced into the calcination reactor 1 to increase the oxygen concentration, accelerate the decomposition of CaCO3 to generate high-temperature CO2 to drive the turbine to generate electricity, shorten the decomposition time and reduce energy consumption. The unreacted oxygen in the exhaust gas is connected to the thermochemical energy storage unit 4 through a pipeline to replace part of the external air.

[0023] The tail gas is preheated by the second heat exchanger 6 and then fed into the thermochemical energy storage unit 4. The oxygen in the tail gas is used to assist the reaction of the thermochemical energy storage unit 4, replacing part of the external air and reducing the energy consumption of gas transportation. The bimetallic oxide can preferably be a material containing Mn and Fe, such as Mn2O3 / Mn3O4 and Fe2O3 / Fe3O4. The reaction formula is as follows (MO_red is the reduced state and MO_ox is the oxidized state): The control system is based on the peak-shaving needs of the power grid. When the power grid is in peak power period and needs to increase power generation, or when wind and solar power generation is insufficient and needs to respond quickly to load demand, the main controller starts the oxygen-enriched calcination process, accelerates the decomposition of CaCO3 by adjusting the oxygen concentration, and uses the oxygen in the exhaust gas to assist the thermochemical energy storage unit in releasing energy, thereby increasing CO2 production and power output.

[0024] The remaining undescribed parts of the present invention may be the same as the prior art, or are well-known technologies, or can be implemented by using the prior art, and will not be described in detail here.

[0025] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A power generation system based on carbonation-calcination cycle coupled with thermochemical energy storage, characterized in that: include: A calcining reactor (1) is used to decompose carbonate at high temperature to generate CaO and CO2 gas; A CO2 turbine power generation unit (2), comprising a turbine (21) and a generator (22), the inlet of which is connected to the CO2 outlet of the calcining reactor (1); a carbonation reactor (3), the inlet of which is connected to the exhaust port of the CO2 turbine power generation unit (2) and the CaO outlet of the calcination reactor (1), respectively, for performing a carbonation reaction between CaO and CO2 to generate CaCO3; A thermochemical energy storage unit (4) comprising a material capable of undergoing a reversible redox reaction; A first heat exchanger (5) is arranged between the thermochemical energy storage unit (4) and the calcination reactor (1), and is used to transfer heat released by the thermochemical energy storage unit (4) in the energy release mode to the calcination reactor (1); A second heat exchanger (6) is arranged between the CO2 turbine power generation unit (2) or the system tail gas waste heat source and the thermochemical energy storage unit (4), and is used to transfer waste heat or heat generated by electric heating to the thermochemical energy storage unit (4), driving it to perform an endothermic reduction decomposition reaction in an energy storage mode; a solid material circulation device (8) connecting the CaCO3 outlet of the carbonation reactor (3) and the CaCO3 inlet of the calcination reactor (1); The control system (10) is configured to control the operation mode and energy distribution of the system according to an external demand signal.

2. The power generation system based on carbonation-calcination cycle coupled with thermochemical energy storage according to claim 1, characterized in that: The reversible redox reaction material in the thermochemical energy storage unit (4) includes one or more combinations of Co3O4 / CoO, Mn2O3 / Mn3O4, BaO2 / BaO, SrO2 / SrO or Fe2O3 / Fe3O4.

3. A power generation system based on carbonation-calcination cycle coupled with thermochemical energy storage according to claim 1 or 2, characterized in that: The power generation system further comprises a heat carrier loop (7) circulating through the first heat exchanger (5), the second heat exchanger (6) and the thermochemical energy storage unit (4) for transferring heat, wherein the heat carrier comprises molten salt, inert gas or liquid metal.

4. The power generation system based on carbonation-calcination cycle coupled with thermochemical energy storage according to claim 1, characterized in that: The second heat exchanger (6) has a switchable connection interface for connecting to an electric heating device or a heater driven by electricity from renewable energy.

5. The power generation system based on carbonation-calcination cycle coupled with thermochemical energy storage according to claim 1, characterized in that: The power generation system further comprises a CO2 diversion device (9) arranged downstream of the exhaust port of the CO2 turbine power generation unit (2) for regulating the flow of CO2 flowing to the carbonation reactor (3) and the flow of CO2 captured and stored.

6. The power generation system based on carbonation-calcination cycle coupled with thermochemical energy storage according to claim 1, characterized in that: The operating temperature of the calcining reactor (1) is 800°C to 1100°C, and the energy release and exothermic reaction temperature of the thermochemical energy storage unit (4) is 800°C to 1000°C.

7. A power generation method based on carbonation-calcination cycle coupled with thermochemical energy storage, characterized in that: The method is applied to a power generation system based on a carbonation-calcination cycle coupled with thermochemical energy storage according to any one of claims 1 to 6, comprising the following modes: Energy storage charging mode: utilizing surplus electric energy or system waste heat to heat the heat carrier through the second heat exchanger (6), driving the material in the thermochemical energy storage unit (4) to undergo an endothermic reduction decomposition reaction, thereby storing energy; Power generation and energy storage coupling mode: utilizing the heat energy stored in the thermochemical energy storage unit (4), heat is supplied to the calcination reactor (1) through the first heat exchanger (5), driving the carbonate decomposition reaction to generate high-temperature CO2, and the CO2 drives the turbine power generation unit (2) to generate electricity; at the same time, the generated CaO enters the carbonation reactor (3) and reacts with CO2 to generate CaCO3, and the solid material circulation device (8) returns the CaCO3 to the calcination reactor (1); Peak load release mode: In response to the increase in grid load demand, the thermochemical energy storage unit (4) is controlled to accelerate the exothermic oxidation reaction, releasing higher intensity heat, which is transferred to the calcination reactor (1) through the first heat exchanger (5), thereby increasing CO2 production and power output.

8. The power generation method based on carbonation-calcination cycle coupled with thermochemical energy storage according to claim 7, characterized in that: In the energy storage charging mode, the energy for driving the thermochemical energy storage unit (4) to perform the endothermic reaction mainly comes from one or more of: cheap off-peak grid electricity, surplus photovoltaic power generation, surplus wind power generation, or waste heat from the exhaust of the CO2 turbine power generation unit (2).

9. The power generation method based on carbonation-calcination cycle coupled with thermochemical energy storage according to claim 7, characterized in that: In the power generation and energy storage coupling mode, part of the CO2 entering the carbonation reactor (3) comes from direct capture of air or industrial flue gas, thereby achieving carbon capture.

10. The power generation method based on carbonation-calcination cycle coupled with thermochemical energy storage according to claim 7, characterized in that: In the peak-shaving energy release mode, part of the CO2 entering the carbonation reactor (3) comes from direct capture of air or industrial flue gas, thereby achieving carbon capture.

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