A supercritical carbon dioxide cycle power generation system and method based on spectral modulation

Abstract

A supercritical carbon dioxide cycle power generation system and method based on spectral modulation is described. The system consists of a solar heating section, a carbon dioxide storage section, a compression section, and a power generation section. The solar heating section includes a radiant heater and a field of mirrors; the carbon dioxide storage section includes an energy balancer (2); the compression section includes a drive motor, a compressor, a cooler, and a regenerator; and the power generation section includes a turbine and a generator. The present invention utilizes a spectral modulation coating to adjust the solar visible spectrum to the infrared band absorbable by carbon dioxide, and exploits the rapid temperature rise properties of solid particles absorbing solar energy. This allows the carbon dioxide to be rapidly heated to a high temperature through radiation-coupled convection before participating in the power generation cycle. A supercritical energy balancer is also provided to balance the intermittent nature of solar energy and to reuse abandoned electricity at night.

Description

Technical Field

[0001] The present invention relates to the technical field of solar power generation, and in particular to a supercritical carbon dioxide cycle power generation system and method based on spectral modulation. Background Art

[0002] Amidst the global energy crisis, there is an urgent need to find reliable renewable energy sources and new power cycles to reduce dependence on traditional fossil fuels. Solar energy, with its advantages of high energy output and easy access, is highly sought after in the energy sector.

[0003] Currently, solar power generation is primarily achieved through photovoltaic conversion and indirect solar thermal utilization. The Landsberg efficiency limit states that the maximum photovoltaic conversion efficiency achievable by photovoltaic generators is approximately 30%. However, actual applications fall far below this limit, hindering the mechanistic limitations of photovoltaic power generation. Concentrated solar power generation currently relies primarily on the Rankine cycle, which uses water as the working fluid. However, since water's absorption of solar energy varies significantly with wavelength, heating water to the high temperatures required by the cycle requires a massive field of mirrors to focus the solar energy, which can lead to environmental problems such as light pollution.

[0004] Supercritical CO2 Brayton cycle power generation technology is environmentally friendly, has high thermal efficiency and good economy, and is considered to be one of the most promising directions for future power generation. However, from the perspective of its current main applications, it still relies on traditional fossil energy as a heat source.

[0005] The demand for electricity shows distinct peaks and valleys during the day and night. Large power plants operating at night often find it difficult to avoid power curtailment, resulting in energy waste. Therefore, combining solar energy with a supercritical CO2 Brayton cycle to recycle this curtailed power is highly valuable. Summary of the Invention

[0006] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a supercritical carbon dioxide cycle power generation system and method based on spectral modulation. Taking into account the temporal intermittent nature of solar energy and the phenomenon of power abandonment during the night operation of existing power generation systems, the supercritical carbon dioxide Brayton cycle is combined with solar energy spectrum modulation technology to realize the process of compressing carbon dioxide to a supercritical state by utilizing the power abandonment at night, and heating the carbon dioxide by utilizing solar energy during the daytime to realize supercritical carbon dioxide cycle power generation.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A supercritical carbon dioxide cycle power generation system based on spectrum modulation, which consists of a solar heating part, a carbon dioxide storage part, a compression part and a power generation part;

[0009] The solar heating section includes a radiant heater 1, a mirror field 9, and related pipelines. A carbon dioxide inlet is provided at the bottom of the radiant heater 1, connected to chamber A of the energy balancer 2 and the regenerator 6, respectively. A carbon dioxide outlet is provided at the top of the radiant heater 1, connected to chamber B of the energy balancer 2 and the turbine 7, respectively. The side of the radiant heater 1 is a light-transmitting area, and the interior of the radiant heater 1 is filled with a radiation-absorbing three-dimensional mesh structure with solar spectrum modulation function. The mirror field 9 is composed of a concentrating flat panel array, which projects light toward the receiving window on the side of the radiant heater 1.

[0010] The carbon dioxide storage portion includes an energy balancer 2 and related pipelines. The energy balancer 2 consists of a chamber A and a chamber B, with a movable sealed partition disposed in between. A carbon dioxide outlet is disposed at the top of chamber A, connected to the carbon dioxide inlet at the bottom of the radiant heater 1 via a pipeline. A carbon dioxide inlet is disposed at the bottom of chamber A, connected to the compressor outlet via a pipeline. A carbon dioxide inlet is disposed at the top of chamber B, connected to the carbon dioxide outlet at the top of the radiant heater 1 and the carbon dioxide inlet of the turbine 7 via pipelines. A carbon dioxide outlet is disposed at the bottom of chamber B, connected to the carbon dioxide inlet of the turbine 7 via a pipeline.

[0011] The compression part includes a drive motor 3, a compressor 4, a cooler 5, a regenerator 6, and related pipelines; the drive motor 3 is coaxially connected to the compressor 4; the inlet of the compressor 4 is connected to the cooler 5, and the outlet of the compressor 4 is connected to the cold-end fluid inlet of the regenerator 6 and the carbon dioxide inlet at the bottom of chamber A in the energy balancer 2 through pipelines; the inlet of the cooler 5 is connected to the hot-end fluid outlet of the regenerator 6 through a pipeline, and the outlet of the cooler 5 is connected to the inlet of the compressor through a pipeline; the regenerator 6 contains cold-end fluid and hot-end fluid channels, the inlet and outlet of the cold-end fluid channel are respectively connected to the outlet of the compressor 4 and the carbon dioxide inlet at the bottom of the radiant heater 1, and the inlet and outlet of the hot-end fluid channel are respectively connected to the outlet of the turbine 7 and the inlet of the cooler 5;

[0012] The power generation part includes a turbine 7, a generator 8 and related pipelines. The inlet of the turbine 7 is connected to the carbon dioxide outlet at the top of the radiation heater 1 and the carbon dioxide outlet at the bottom of chamber B, and the outlet of the turbine 7 is connected to the inlet of the fluid channel at the hot end of the regenerator 6; the generator 8 is coaxially connected to the turbine 7.

[0013] The operating method of the supercritical carbon dioxide cycle power generation system based on spectral modulation includes the following steps:

[0014] Step 1: Nighttime CO2 Compression

[0015] The carbon dioxide is compressed to a supercritical state using the abandoned electricity at night and sent to the energy balancer 2 for temporary storage: the carbon dioxide that has completed work leaves the turbine 7, passes through the regenerator 6 for cooling, and then enters a multi-stage compression system consisting of a compressor 4, a cooler 5, and a drive motor 3 with staged compression and inter-stage cooling. The turbine is decoupled from the multi-stage compression system. The drive motor 3 uses the abandoned electricity to compress the carbon dioxide to a supercritical state and then sends it to chamber A of the energy balancer 2 for storage through a pipeline. As the carbon dioxide increases, the partition in the energy balancer 2 moves toward chamber B until it reaches the upper limit of the partition's movement position and stops moving, completing the carbon dioxide compression;

[0016] Step 2: Daytime supercritical carbon dioxide cycle power generation

[0017] Supercritical carbon dioxide leaves chamber A of the energy balancer 2, enters from the bottom of the radiation heater 1, passes through the three-dimensional mesh structure and heats up before leaving. It then enters the turbine 7 for expansion and work, and the generator generates electricity. The carbon dioxide enters the regenerator 6 and its temperature drops. It then enters a multi-stage compression system consisting of a compressor 4, a cooler 5, and a drive motor 3 for staged compression and inter-stage cooling. After passing through chamber A of the energy balancer 2, it tangentially enters the interior space of the radiation heater 1 from the bottom. After its temperature rises, it leaves and enters the turbine 7 for expansion and work, and then enters the regenerator 6 for cooling. The above process is repeated. During stable operation, the partition in the energy balancer 2 moves to the minimum volume position of chamber A, and no carbon dioxide is stored.

[0018] Step 3: Buffer storage of high-temperature supercritical carbon dioxide

[0019] When there is excess solar radiation or the power generation exceeds the power demand, part of the high-temperature supercritical carbon dioxide after passing through the radiation heater 1 in step 2 is bypassed to chamber B in the energy balancer 2 for storage until the movable baffle moves to the maximum volume of chamber B and the pipeline is bypassed; when the power generation power increases, the carbon dioxide in chamber B in the energy balancer 2 is sent to the turbine 7 to perform work.

[0020] The radiation heat absorber 1 includes an outer light-transmitting structure, an inner three-dimensional mesh structure, and a carbon dioxide inlet and outlet; the outer light-transmitting structure of the radiation heat absorber 1 receives solar energy focused and projected by the mirror field, and has a transmittance greater than 0.9; the inner three-dimensional mesh structure of the radiation heat absorber 1 consists of three parts: a three-dimensional support network, a surface spectrum modulation coating, and node particles; the carbon dioxide inlet uses dual-channel hedging to form an upward rotating flow field.

[0021] The basic unit bodies of the three-dimensional support network inside the radiation heat absorber 1 include rectangular, circular, and honeycomb types, and can be made of materials with good high temperature resistance and resistance to high temperature supercritical carbon dioxide, such as martensitic stainless steel, low alloy steel T22, ferromartensitic steel P92, and austenitic steel Super304H.

[0022] The node particles inside the radiation heat absorber 1 have a particle size range of 0.1-3 mm. The node particles can be made of aluminum oxide, silicon carbide, coke, copper chrome black, and the three-dimensional network structure is materialized through 3D printing technology.

[0023] The surface spectrum modulation coating inside the radiation heat absorber 1 is attached to the surface of the three-dimensional support network by spraying. The coating is gold nanoparticles and Ba2Y(BO3)2Cl prepared by high temperature solid phase method doped with Ce at a certain concentration ratio. 3+ :Yb 3+ The concentration ratio of the nanoparticle mixture is 0.03:(0.005-0.3), and the concentration ratio of the gold nanoparticles to the nanoparticle mixture is 1:(5-20).

[0024] A counter-flow deflector is provided at the carbon dioxide inlet at the bottom of the radiation heat absorber 1, and two air flows counter-flow and enter the internal space of the radiation heat absorber 1 along a tangential direction, forming a rotating upward flow state.

[0025] The bottom of the middle sealing partition in the energy balancer 2 adopts a serrated structure and fits into the bottom protrusion of the energy balancer 2. The contact surfaces of the two are coated with solid lubricant, such as graphite powder. The movement of the partition is mainly controlled by the pressure difference of carbon dioxide in chambers A and B, and mechanically assisted control. In this way, space utilization is improved and the storage space of supercritical carbon dioxide in two temperature states is reduced.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] This invention utilizes the rapid heating of supercritical carbon dioxide by solid particles absorbing solar energy, and a composite nanocoating that modulates the visible spectrum of solar energy to the infrared region where carbon dioxide can absorb radiation. This method achieves convection-coupled radiation heating of supercritical carbon dioxide. Its three-dimensional network structure stabilizes the spatial distribution of the solid particles, controlling the radiation field and facilitating the heating of the carbon dioxide. An energy balancer is employed to balance the intermittent nature of solar energy and the mismatch between nighttime electricity supply and demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the supercritical carbon dioxide cycle power generation system based on spectral modulation of the present invention.

[0029] Figure 2 Schematic diagram of the radiation heater structure.

[0030] Figure 3 This is a side schematic diagram of the energy balancer B chamber. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] like Figure 1 As shown, a supercritical carbon dioxide cycle power generation system based on spectral modulation is composed of a solar heating part, a carbon dioxide storage part, a compression part and a power generation part.

[0033] like Figure 1 As shown, the solar heating part includes a radiation heater 1, a mirror field 9, and related pipelines. A carbon dioxide inlet is provided at the bottom of the radiation heater 1, which is connected to the chamber in the energy balancer 2 and the regenerator 6 respectively. A carbon dioxide outlet is provided at the top of the radiation heater 1, which is connected to the B chamber in the energy balancer 2 and the turbine 7 respectively. Figure 2 As shown, the side of the radiation heater 1 is a light-transmitting area, and the interior of the radiation heater 1 is filled with a radiation-absorbing three-dimensional mesh structure with a solar spectrum modulation function; the mirror field 9 is composed of a focusing flat panel array, which projects toward the receiving window on the side of the radiation heater 1.

[0034] like Figure 1 As shown, the carbon dioxide storage section includes an energy balancer 2 and its associated piping. Energy balancer 2 consists of chambers A and B, with a removable sealed partition positioned between them. Chamber A has a carbon dioxide outlet at the top, connected via piping to the carbon dioxide inlet at the bottom of the radiant heater 1. Chamber A also has a carbon dioxide inlet at the bottom, connected via piping to the compressor outlet. Chamber B has a carbon dioxide inlet at the top, connected via piping to the carbon dioxide outlet at the top of the radiant heater 1 and the carbon dioxide inlet of turbine 7. Chamber B also has a carbon dioxide outlet at the bottom, connected via piping to the carbon dioxide inlet of turbine 7.

[0035] The compression section includes a drive motor 3, a compressor 4, a cooler 5, a regenerator 6, and related piping. The drive motor 3 is coaxially connected to the compressor 4; the compressor 4 inlet is connected to the cooler 5, and the compressor 4 outlet is connected via pipelines to the cold-end fluid inlet of the regenerator 6 and the carbon dioxide inlet at the bottom of chamber A in the energy balancer 2. The cooler 5 inlet is connected to the hot-end fluid outlet of the regenerator 6 via a pipeline, and the cooler 5 outlet is connected to the compressor inlet via a pipeline. The regenerator 6 contains cold-end fluid and hot-end fluid channels. The inlet and outlet of the cold-end fluid channel are respectively connected to the compressor 4 outlet and the carbon dioxide inlet at the bottom of the radiant heater 1, while the inlet and outlet of the hot-end fluid channel are respectively connected to the turbine 7 outlet and the cooler 5 inlet.

[0036] The power generation section includes a turbine 7, a generator 8, and associated piping. The turbine 7's inlet and outlet are connected to the CO2 outlet at the top of the radiant heater 1, the CO2 outlet at the bottom of chamber B, and the inlet of the hot-end fluid channel of the regenerator 6, respectively. Generator 8 is coaxially connected to turbine 7.

[0037] Implementation case: Figure 1As shown, the system operation includes three parts.

[0038] Step 1: Nighttime CO2 Compression

[0039] By utilizing the power curtailment at night, the carbon dioxide that has completed its work has a pressure of 9.8 MPa and a temperature of 36°C. After leaving the turbine 7 and cooling through the regenerator 6, it enters a multi-stage compression system consisting of a compressor 4, a cooler 5, and a drive motor 3 with staged compression and inter-stage cooling. The turbine and the multi-stage compression system are in a decoupled state. The drive motor 3 uses the curtailed power to drive the compressor 4 to operate and compress the carbon dioxide. After the pressure rises to 14.1 MPa and the temperature reaches 46°C, it is transported to chamber A in the energy balancer 2 through a pipeline for storage. The partition in the energy balancer 2 moves toward chamber B until it reaches the upper limit of chamber A and stops moving.

[0040] Step 2: Daytime supercritical carbon dioxide cycle power generation

[0041] Supercritical carbon dioxide leaves chamber A of energy balancer 2 and enters the interior space of radiant heater 1 in a rotating flow pattern from the bottom. After being heated by the three-dimensional network structure to 300°C, it exits and enters turbine 7, where it expands and generates work, driving the generator to generate electricity. The outlet pressure of turbine 7 is 10 MPa and the temperature is 250°C. After entering regenerator 6, where the temperature is lowered, the carbon dioxide enters a multi-stage compression system consisting of compressor 4, cooler 5, and drive motor 3, where its pressure is raised to 14 MPa. After passing through chamber A of energy balancer 2, it enters the interior space of radiant heater 1 tangentially from the bottom. After its temperature rises to 300°C, it exits and enters turbine 7, where it expands and generates work. It then enters regenerator 6 for cooling, repeating this process. During stable operation, the partition in energy balancer 2 moves to the minimum volume position of chamber A, and no carbon dioxide is stored.

[0042] Step 3: Buffer storage of high-temperature supercritical carbon dioxide

[0043] When solar radiation is excessive or power generation exceeds electricity demand, the high-temperature supercritical carbon dioxide produced after passing through radiant heater 1 in step 2 is partially bypassed and stored in chamber B of energy balancer 2 until the movable baffle moves to the maximum volume of chamber B, where storage stops. When power generation increases but solar radiation is weak, the carbon dioxide in chamber B of energy balancer 2 is sent to turbine 7 to perform work.

Claims

1. A supercritical carbon dioxide cycle power generation system based on spectral modulation, characterized by: The system consists of a solar heating part, a carbon dioxide storage part, a compression part, and a power generation part; The solar heating part includes a radiation heater (1), a mirror field (9) and related pipelines; a carbon dioxide inlet is provided at the bottom of the radiation heater (1), which is respectively connected to the A chamber of the energy balancer (2) and the regenerator (6); a carbon dioxide outlet is provided at the top of the radiation heater (1), which is respectively connected to the B chamber of the energy balancer (2) and the turbine (7); the side of the radiation heater (1) is a light-transmitting area, and the interior of the radiation heater (1) is filled with a radiation-absorbing three-dimensional mesh structure with a solar spectrum modulation function; the mirror field (9) is composed of a focusing flat panel array, which projects toward the receiving window on the side of the radiation heater (1); The carbon dioxide storage part includes an energy balancer (2) and related pipelines. The energy balancer (2) consists of chamber A and chamber B, with a movable sealed partition arranged in the middle; wherein a carbon dioxide outlet is arranged at the upper part of chamber A, which is connected to the carbon dioxide inlet at the bottom of the radiation heater (1) through a pipeline; a carbon dioxide inlet is arranged at the lower part of chamber A, which is connected to the compressor outlet through a pipeline; a carbon dioxide inlet is arranged at the upper part of chamber B, which is connected to the carbon dioxide outlet at the upper part of the radiation heater (1) and the carbon dioxide inlet of the turbine (7) through pipelines respectively; a carbon dioxide outlet is arranged at the lower part of chamber B, which is connected to the carbon dioxide inlet of the turbine (7) through a pipeline; The compression part includes a driving motor (3), a compressor (4), a cooler (5), a regenerator (6) and related pipelines; the driving motor (3) is coaxially connected to the compressor (4); the inlet of the compressor (4) is connected to the cooler (5), and the outlet of the compressor (4) is respectively connected to the cold-end fluid inlet of the regenerator (6) and the carbon dioxide inlet at the bottom of chamber A in the energy balancer (2) through pipelines; the inlet of the cooler (5) is connected to the hot-end fluid outlet of the regenerator (6) through a pipeline, and the outlet of the cooler (5) is connected to the inlet of the compressor through a pipeline; the regenerator (6) contains cold-end fluid and hot-end fluid channels, the inlet and outlet of the cold-end fluid channel are respectively connected to the outlet of the compressor (4) and the carbon dioxide inlet at the bottom of the radiation heater (1), and the inlet and outlet of the hot-end fluid channel are respectively connected to the outlet of the turbine (7) and the inlet of the cooler (5); The power generation part includes a turbine (7), a generator (8) and related pipelines. The inlet of the turbine (7) is connected to the carbon dioxide outlet at the upper part of the radiation heater (1) and the carbon dioxide outlet at the lower part of chamber B. The outlet of the turbine (7) is connected to the inlet of the hot end fluid channel of the regenerator (6). The generator (8) is coaxially connected to the turbine (7). The radiation heater (1) is composed of an outer light-transmitting structure, an inner three-dimensional mesh structure, and a carbon dioxide inlet and outlet. The outer light-transmitting structure of the radiation heater (1) receives solar energy focused and projected by the mirror field, and has a light transmittance greater than 0.9; the inner three-dimensional mesh structure of the radiation heater (1) is composed of three parts: a three-dimensional support network, a surface spectrum modulation coating, and node particles; the carbon dioxide inlet at the bottom of the radiation heater (1) adopts a double-channel counter-attack to form an upward rotating flow field; The surface spectrum modulation coating inside the radiation heater (1) is attached to the surface of the three-dimensional support network by spraying, and the coating is gold nanoparticles and Ba2Y(BO3)2Cl prepared by a high-temperature solid phase method doped with Ce at a certain concentration ratio. 3+ :Yb 3+ The concentration ratio of gold nanoparticles to nanoparticle mixture is 0.03:(0.005 - 0.3), and the concentration ratio of gold nanoparticles to nanoparticle mixture is 1:(5 -20); The bottom of the middle sealing partition in the energy balancer (2) adopts a sawtooth structure and fits with the bottom protrusion of the energy balancer (2), and the contact surface of the two is coated with a solid lubricant. The movement of the partition is controlled by the pressure difference of the carbon dioxide in the A chamber and the B chamber and mechanical auxiliary control. In this way, the space utilization rate is improved and the storage space of the supercritical carbon dioxide in the two temperature states is reduced.

2. The supercritical carbon dioxide cycle power generation system based on spectral modulation according to claim 1, characterized in that: The basic unit bodies of the three-dimensional support network inside the radiation heater (1) include rectangular, circular, and honeycomb types, and are made of materials with good high temperature resistance and resistance to high temperature supercritical carbon dioxide.

3. The supercritical carbon dioxide cycle power generation system based on spectral modulation according to claim 2, characterized in that: The material having good high temperature resistance and high temperature supercritical carbon dioxide resistance is martensitic stainless steel, low alloy steel T22, ferro-martensitic steel P92 or austenitic steel Super304H.

4. The supercritical carbon dioxide cycle power generation system based on spectral modulation according to claim 1, characterized in that: The node particles inside the radiation heater (1) have a particle size range of 0.1-3 mm, and the node particles are made of aluminum oxide, silicon carbide, coke, and copper chromium black, and the three-dimensional network structure is materialized through 3D printing technology.

5. The supercritical carbon dioxide cycle power generation system based on spectral modulation according to claim 1, characterized in that: A counter-flow deflector is provided at the carbon dioxide inlet at the bottom of the radiation heater (1), and two air flows counter-flow and enter the internal space of the radiation heater (1) along a tangential direction, forming a rotating upward flow state.

6. The operating method of a supercritical carbon dioxide cycle power generation system based on spectral modulation according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: Nighttime CO2 Compression The carbon dioxide is compressed to a supercritical state by using the abandoned electricity at night and sent to the energy balancer (2) for temporary storage. Specifically, the carbon dioxide that has done work leaves the turbine (7) and is cooled by the regenerator (6) and then enters a multi-stage compression system composed of a compressor (4), a cooler (5), and a drive motor (3) with staged compression and inter-stage cooling. The turbine is decoupled from the multi-stage compression system. The drive motor (3) uses the abandoned electricity to compress the carbon dioxide to a supercritical state and then sends it to the A chamber of the energy balancer (2) for storage through a pipeline. As the carbon dioxide increases, the partition in the energy balancer (2) moves toward the B chamber until it reaches the upper limit of the partition's movement position and stops moving, and the carbon dioxide compression is completed. Step 2: Daytime supercritical carbon dioxide cycle power generation Supercritical carbon dioxide leaves chamber A of the energy balancer (2) and enters from the bottom of the radiation heater (1). After passing through the three-dimensional mesh structure and increasing in temperature, it leaves the chamber and enters the turbine (7) to expand and perform work. The generator generates electrical energy. After the carbon dioxide enters the regenerator (6) and decreases in temperature, it enters a multi-stage compression system consisting of a compressor (4), a cooler (5), and a drive motor (3) for staged compression and inter-stage cooling. After passing through chamber A of the energy balancer (2), it enters the internal space of the radiation heater (1) tangentially from the bottom of the radiation heater (1). After increasing in temperature, it leaves the chamber and enters the turbine (7) to expand and perform work. It then enters the regenerator (6) for cooling. The above process is repeated. During stable operation, the partition in the energy balancer (2) moves to the minimum volume position of chamber A and no carbon dioxide is stored. Step 3: Buffer storage of high-temperature supercritical carbon dioxide When there is excess solar radiation or the power generation is greater than the power demand, part of the high-temperature supercritical carbon dioxide after passing through the radiation heater (1) in step 2 is bypassed to the B chamber in the energy balancer (2) for storage until the movable partition moves to the maximum volume of the B chamber; when the power generation increases, the carbon dioxide in the B chamber in the energy balancer (2) is sent to the turbine (7) to perform work.

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