A low-temperature liquid alloy-based carbon dioxide capture and solid carbon generation system

Abstract

The application relates to a low-temperature liquid alloy-based carbon dioxide capturing and solid carbon generating system, which comprises an absorption subsystem, an electrochemical reaction subsystem and a product separation chamber, the absorption subsystem comprises an absorption tower, the lower end of the absorption tower is provided with an air inlet pipe for receiving flue gas of a coal-fired power plant, the upper end of the absorption tower is provided with a liquid inlet pipe, the other end of the liquid inlet pipe is connected with the product separation chamber, the system contains circulating organic solution, the liquid inlet pipe is used for receiving the organic solution, the organic solution absorbs carbon dioxide in the flue gas in the absorption tower, the bottom end of the absorption tower is provided with a liquid outlet, the liquid outlet is connected with a liquid outlet pipe, the other end of the liquid outlet pipe is connected with the electrochemical reaction subsystem, the liquid outlet and the liquid outlet pipe jointly guide the organic solution rich in carbon dioxide into the electrochemical reaction subsystem, the electrochemical reaction subsystem is provided with liquid alloy, and the liquid alloy is used for reducing the carbon dioxide into solid carbon.

Description

Technical Field

[0001] This invention relates to the fields of energy and environment, and in particular to a carbon dioxide capture and solid carbon generation system based on cryogenic liquid alloys. Background Technology

[0002] The large-scale development and use of fossil fuels has led to a continuous rise in atmospheric carbon dioxide concentration. According to incomplete statistics, by 2020, the global atmospheric carbon dioxide concentration had reached nearly 420 ppm, with an average annual absolute increase of 2.4 ppm over the past 10 years. By 2035, carbon dioxide emissions may exceed 40 Gt. In recent years, the escalating greenhouse effect has also attracted widespread attention. While the first three industrial revolutions brought humanity into an era of unprecedented prosperity, they also resulted in enormous energy and resource consumption, drastically widening the conflict between humanity and nature. This has triggered the fourth industrial revolution of our time—the green industrial revolution—whose primary goal is to achieve "decoupling" from carbon emissions.

[0003] Currently, most of my country's coal-fired power plant carbon dioxide emission reduction demonstration projects are carbon dioxide capture and storage (CCS) projects. However, the close connection between carbon dioxide capture and subsequent treatment is key to increasing the feasibility of CCS. As an upstream link in CCS, carbon dioxide capture faces the problem of high energy consumption due to rich liquid regeneration, and the investment and operating costs of the capture system (~300 yuan / ton CO2) are relatively high due to the low partial pressure of carbon dioxide in the flue gas. As a downstream link in CCS, carbon dioxide storage has more stringent conditions for safe storage and carries risks such as damage to geological structures and carbon dioxide leakage.

[0004] Electrochemical technology can reduce carbon dioxide into value-added gaseous fuels such as carbon monoxide, methane, ethylene, and syngas, which are widely used as basic raw materials in chemical production. Ethylene, as the foundation of the polymer industry, occupies a core position in the petrochemical industry. Methane is a major component of natural gas. Electrochemical technology can also reduce carbon dioxide into liquid fuels such as formic acid, methanol, and ethanol. Formic acid has high added value and can be used as a raw material for formate batteries and hydrogen storage materials; it is an important chemical intermediate in many industrial processes. Methanol can serve as a potential alternative to future fossil fuels. Ethanol, as an energy source, plays a crucial role in the medical and chemical industries. However, the subsequent utilization of these products often leads to the re-emission of greenhouse gases. In recent years, research on reducing carbon dioxide to solid carbon using molten salt electrolysis technology has increased. However, traditional molten salt electrolysis technology requires high temperatures (>600 °C) and inevitably leads to coking, which hinders the continuous reaction. Liquid alloy-based catalysts possess special physical properties that can effectively prevent coking of solid products on the catalyst surface. In recent years, gallium-based liquid alloys have made groundbreaking progress in the electro / thermochemical conversion of carbon dioxide into solid carbon. However, the strong corrosiveness of metallic gallium to steel structures limits the large-scale application of gallium-based liquid alloys. Summary of the Invention

[0005] The present invention aims to overcome the defects of the prior art by providing a carbon dioxide capture and solid carbon generation system based on cryogenic liquid alloy. The system utilizes cryogenic alloy to reduce carbon dioxide in flue gas from coal-fired power plants into solid carbon at near room temperature, thereby achieving negative carbon emissions and further improving the production efficiency of coal-fired power plants.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A carbon dioxide capture and solid carbon generation system based on cryogenic liquid alloys includes an absorption subsystem, an electrochemical reaction subsystem, and a product separation chamber.

[0008] The absorption subsystem includes an absorption tower with an inlet pipe at its lower end for receiving flue gas from a coal-fired power plant, and a liquid inlet pipe at its upper end connected to a product separation chamber at the other end of the liquid inlet pipe.

[0009] The system contains a circulating organic solution, and the inlet pipe is used to receive the organic solution, which absorbs carbon dioxide from the flue gas within the absorption tower.

[0010] The absorber tower is equipped with a liquid outlet at its bottom, which is connected to a liquid outlet pipe. The other end of the liquid outlet pipe is connected to an electrochemical reaction subsystem. The liquid outlet and the liquid outlet pipe work together to introduce a carbon dioxide-rich organic solution into the electrochemical reaction subsystem.

[0011] The electrochemical reaction subsystem includes a liquid alloy used to reduce carbon dioxide into solid carbon.

[0012] The electrochemical reaction subsystem is provided with a manifold at one end, and the other end of the manifold is connected to the product separation chamber. The manifold is used to introduce the organic solution containing reduced solid carbon and carbon dioxide into the product separation chamber.

[0013] Furthermore, a gas distributor is provided at one end of the air inlet pipe inside the absorption tower, a liquid distributor is provided below one end of the liquid inlet pipe inside the absorption tower, and a demister is provided above one end of the liquid inlet pipe inside the absorption tower. The demister is used to remove mist from the flue gas after carbon dioxide reduction.

[0014] Furthermore, the liquid distributor is a tubular liquid distributor and the gas distributor is an elongated orifice gas distributor. The tubular liquid distributor and the elongated orifice gas distributor allow the organic solution and flue gas to enter the absorption tower more evenly, increasing the contact area between the two.

[0015] Furthermore, a multi-layered packing material with the same structure is provided between the air inlet pipe and the liquid inlet pipe. Packing pressure plates are provided above and below the packing material. The packing pressure plates are used to press the packing material to prevent it from loosening or jumping under the action of the fluid. The absorption tower is provided with multiple manholes for observing the packing material.

[0016] Furthermore, the packing material is a modified plastic packing material. Stainless steel perforated plate corrugated packing is the main choice for carbon dioxide capture systems due to its excellent performance, but it is expensive. Inexpensive plastic packing materials offer advantages such as large porosity and throughput, low resistance, low energy consumption and operating costs, light weight, easy installation and removal, and reusability, which can reduce the cost of the packing material by up to 50%. To address the problems of poor surface hydrophilicity and low strength of plastic packing materials, the plastic packing material is modified. [1] It has great application prospects for carbon capture and absorption, and is more suitable as a distribution device for the dispersion of flue gas and organic solutions in this invention.

[0017] Furthermore, a liquid redistributor is provided between the two layers of packing in the middle of the absorption tower, and an interstage cooler is provided below the liquid redistributor. The interstage cooler is used to lower the temperature of part of the organic solution, thereby reducing the equilibrium partial pressure of carbon dioxide gas, enhancing the ability of the organic solution to carry carbon dioxide, and improving the absorption efficiency.

[0018] Furthermore, the top of the absorption tower is provided with an outlet, and an outlet pipe is connected to the outlet. The outlet is used to discharge flue gas with reduced carbon dioxide, and the other end of the outlet pipe is connected to a chimney.

[0019] Furthermore, the electrochemical reaction subsystem also includes multiple sets of reaction devices, a distribution manifold, and an exhaust pipe. The distribution manifold is connected to the liquid outlet pipe and is used to introduce the carbon dioxide-rich organic solution into the multiple sets of reaction devices respectively.

[0020] One end of the reaction device is connected to the branch manifold, and the other end of the reaction device is connected to the main manifold through a branch pipe. The exhaust pipe is located on the branch pipe and is used to discharge the oxygen generated by the reaction and the unreacted flue gas.

[0021] Furthermore, multiple sets of the aforementioned reaction devices are stacked in parallel to enable large-scale production and application.

[0022] Furthermore, the reaction apparatus includes a reaction vessel and a power source, the reaction vessel and the power source are connected, the reaction vessel is provided with a flow channel, the flow channel wall is provided with a counter electrode, and the bottom of the reaction vessel is provided with a liquid alloy electrode array (working electrode).

[0023] The liquid alloy electrode array comprises conductive carbon fibers, an electrode substrate, a capillary glass tube, and a liquid alloy. The electrode substrate is connected to the inside of the bottom of the reaction vessel, and the capillary glass tube is fixed above the electrode substrate.

[0024] The electrode substrate has a groove, and the capillary glass tube contains conductive carbon fibers. The bottom end of the conductive carbon fibers is located in the groove of the electrode substrate, and the main wire of the conductive carbon fibers is connected to the negative terminal of the power supply. Liquid alloy is applied to the conductive fibers at the end of the capillary glass tube. By moving the capillary glass tube inside the liquid melt, droplets of liquid alloy are attached to the conductive carbon fibers. The high surface tension of the liquid alloy allows it to maintain its original shape during the electrochemical reaction. Furthermore, the counter electrode is an iron electrode.

[0025] Furthermore, the conductive carbon fiber extends 0.3-0.8 cm, preferably 0.5 cm, from the top of the capillary glass tube, and is in contact with the liquid alloy. The conductive carbon fiber is used to charge the liquid alloy.

[0026] Furthermore, the product separation chamber is equipped with a filter screen, which is used to separate solid carbon and organic solution with reduced carbon dioxide. The organic solution with reduced carbon dioxide is introduced into the absorption tower through the inlet pipe by a lean liquid pump.

[0027] Furthermore, this invention also provides a method for using a carbon dioxide capture and solid carbon generation system based on a cryogenic liquid alloy, the specific steps of which are as follows:

[0028] S1. Before the reaction, an organic solution is introduced into the system. The organic solution enters the absorption tower through the liquid inlet pipe. The flue gas from the coal-fired power plant enters the absorption tower through the gas inlet pipe. The organic solution absorbs the carbon dioxide in the flue gas, resulting in an organic solution rich in carbon dioxide and flue gas with reduced carbon dioxide content.

[0029] S2. The carbon dioxide-rich organic solution obtained in step S1 is sequentially introduced into multiple sets of reaction devices through the liquid outlet pipe and the diversion manifold. Under the action of external bias voltage, carbon dioxide and liquid alloy undergo a reduction reaction on the surface of liquid alloy to generate solid carbon, while oxygen evolution reaction occurs on the counter electrode (anode side) to generate oxygen.

[0030] S3. The solid carbon obtained in step S2 and the organic solution with reduced carbon dioxide are introduced into the product separation chamber, separated by a filter screen, and the organic solution with reduced carbon dioxide is introduced into the absorption tower through the inlet pipe.

[0031] Further, in step S1, the flue gas from the coal-fired power plant is injected downwards into the absorption tower through the inlet pipe and gas distributor. It then flows upwards, contacting the organic solution sprayed down through the liquid inlet pipe and liquid distributor. This organic solution absorbs carbon dioxide from the flue gas, resulting in a carbon dioxide-rich organic solution and flue gas with reduced carbon dioxide levels. The reduced carbon dioxide flue gas is then demisted by a demister before leaving the absorption tower through the outlet pipe and being discharged into the atmosphere through the chimney. Further, in step S1, the flue gas from the coal-fired power plant undergoes pretreatment for denitrification, dust removal, and desulfurization.

[0032] Furthermore, in step S1, the flue gas temperature of the coal-fired power plant is 40 ℃-60 ℃, providing a suitable temperature for the absorption and reaction of carbon dioxide.

[0033] Furthermore, in step S1, the organic solution has an absorption rate of over 90% for carbon dioxide in the flue gas, and the organic solution is ethanolamine-methyldiethanolamine.

[0034] Furthermore, the oxygen obtained in step S2 is discharged through the exhaust pipe, collected and processed, and then introduced into the furnace to promote the combustion of pulverized coal, thereby improving the combustion efficiency of the boiler and thus achieving continuous and stable operation of the entire system.

[0035] Furthermore, in step S2, the adhesion rate of the liquid alloy on the capillary glass tube is higher than 95%, and the liquid alloy is a Bi-In-Sn based liquid alloy.

[0036] Furthermore, in step S2, the external bias voltage is an external potential of -330 mV.vs CO2 / C.

[0037] Furthermore, in step S2, the counter electrode is immersed below the surface of the organic solution, and the liquid alloy electrode array is submerged in the organic solution to form a circuit. The counter electrode and the liquid alloy electrode array do not come into contact, thus avoiding short circuits and ensuring the safe and efficient operation of the reaction system.

[0038] Further, in step S3, the solid carbon obtained in step S2 floats on the surface of the organic solution. The solid carbon obtained in step S2 and the organic solution with reduced carbon dioxide are introduced into the product separation chamber through the manifold. After being separated by a filter screen, the organic solution with reduced carbon dioxide is introduced into the absorption tower through the inlet pipe under the action of the lean liquid pump.

[0039] The principle of this invention is as follows:

[0040] Throughout the process, the organic solution only serves to dissolve carbon dioxide. The reduction of carbon dioxide is driven by an external bias voltage on the surface of the Bi-In-Sn liquid alloy droplet. Specifically, on the cathode side, the Bi-In-Sn-based liquid alloy catalyst LA, under the influence of an external bias voltage, reduces carbon dioxide to solid carbon via a four-electron reaction, while itself is oxidized to LAO. x Due to the application of a reduction potential, LAO x It can be reduced back to its original LA state, while generating OH. - This regeneration of the catalyst is achieved, and simultaneously, an oxygen evolution reaction occurs on the anode side, generating OH-. - It will migrate to the anode side, lose electrons, and be oxidized into oxygen, thus closing the catalytic cycle.

[0041] Due to the unique properties of the liquid alloy, the solid carbon generated in the reaction automatically detaches from the surface of the liquid alloy. Based on the density difference between the solid carbon and the organic solution, the solid carbon automatically floats on the surface of the organic solution. Carbon products with different morphologies can be applied in various fields such as catalysis, construction, and batteries, or sold as economic products. The low-carbon dioxide concentration organic solvent is transported to the absorber system via a lean-liquid pump to redissolve the carbon dioxide, achieving system circulation. Correspondingly, the gaseous product oxygen on the anode side is further collected and processed through the exhaust pipe and introduced into the furnace to promote the combustion of pulverized coal, thereby improving the boiler's combustion efficiency. This reaction method effectively avoids coking, allows the reaction to proceed continuously, and enables rapid and simple separation of the products.

[0042] The adhesion rate of the liquid alloy on the capillary glass tube is at least 95%. To ensure the adhesion rate, it is necessary to study the flow characteristics and flow distribution of the fluid in a multi-branch parallel reactor. Numerical calculations, using the Bajura and Wang mathematical models, predict the flow and pressure distribution in the parallel reactor system, providing a means for the above research. Changes in pipe diameter, the number of parallel reactors, and the inlet and outlet pressure difference all affect the flow distribution. Due to its own diversion effect, the fluid velocity in the split manifold continuously decreases, approaching zero at the end of the pipe; while the fluid velocity in the confluence manifold continuously increases, reaching its maximum at the outlet. During the flow process, due to inertia, the fluid generates vortex regions of varying intensities at the connection points between the split manifold and each parallel reactor, as well as within the confluence manifold, significantly impacting the fluid. By adjusting the dimensions of various parts of the reactor, the number of parallel reactors, and the inlet and outlet pressures, the flow distribution in each parallel reactor can be made more uniform, thereby ensuring the continuous and efficient operation of the electrochemical reaction chamber. Furthermore, based on the above numerical optimization, a liquid distributor can be added to further improve the flow uniformity.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] 1. This invention converts carbon dioxide into solid carbon and oxygen on the surface of a liquid alloy in a near-room temperature environment. The reaction has low requirements and is rapid. The reaction products can automatically peel off from the surface of the liquid alloy and float on the surface of the organic solution, which facilitates the subsequent separation of the products and effectively avoids coking. This allows the reaction to proceed continuously and complete the effective conversion of carbon dioxide.

[0045] 2. The product generated by the reaction of carbon dioxide in this invention is solid carbon (nano-carbon product), which avoids the carbon-containing product returning to the atmosphere in the form of carbon dioxide.

[0046] 3. This invention couples carbon dioxide capture from coal-fired power plants with Bi-In-Sn-based liquid alloy electrochemical conversion of CO2 into solid carbon technology. Compared with existing flue gas treatment systems for coal-fired power plants, this invention achieves negative carbon emissions from coal-fired power plants while improving their operating efficiency.

[0047] 4. By using this system, carbon dioxide can be conveniently reduced to solid carbon, which not only makes rational use of resources, but also realizes the capture and utilization of carbon dioxide, which is of great significance for energy conservation and carbon reduction of coal-fired power generating units.

[0048] 5. The solid carbon materials converted from CO2 by this system can be used in various fields such as catalysis, construction, and batteries, contributing to the development of energy storage and new energy technologies, and are expected to achieve large-scale application.

[0049] 6. The system provided by this invention has a cost of RMB 230 for processing one ton of carbon dioxide, which is nearly 50% lower than the cost of a CCS project (~RMB 450 / ton (CO2)). The system has a maximum carbon capture rate of 92% and a maximum carbon conversion rate of 89%.

[0050] 7. This invention uses a tubular liquid distributor and a long-slot gas distributor to make the organic solution and flue gas more evenly dispersed into the absorption tower, increasing the contact area between the two. The setting of the flow direction of the organic solution and flue gas, as well as the packing, also make its effect more obvious. Attached Figure Description

[0051] Figure 1 This is a simplified flow diagram of the carbon dioxide capture and solid carbon generation system in this invention;

[0052] Figure 2 This is a schematic diagram of the carbon dioxide capture and solid carbon generation system in this invention;

[0053] Figure 3 This is a schematic diagram of the structure of the reaction subsystem of the present invention;

[0054] Figure 4 This is a schematic diagram of the electrochemical reaction subsystem of the present invention;

[0055] Figure 5 This is a schematic diagram of the reaction apparatus of the present invention;

[0056] Figure 6 This is a schematic diagram of the liquid alloy electrode array of the present invention;

[0057] Explanation of the attached drawing numbers:

[0058] 1. Absorption subsystem; 11. Absorption tower; 12. Gas outlet pipe; 13. Gas outlet; 14. Demister; 15. Liquid inlet pipe; 16. Liquid distributor; 17. Packing pressure plate; 18. Packing; 19. Manhole; 110. Liquid redistributor; 111. Interstage cooler; 112. Gas inlet pipe; 113. Gas distributor; 114. Liquid outlet; 115. Liquid outlet pipe.

[0059] 2. Electrochemical reaction subsystem; 21. Diverter manifold; 22. Reaction apparatus; 23. Manifold; 24. Exhaust pipe; 221. Reaction vessel; 222. Counter electrode; 223. Liquid alloy electrode array (working electrode); 2231. Conductive carbon fiber; 2232. Electrode substrate; 2233. Capillary glass tube; 2234. Liquid alloy; 224. Flow channel.

[0060] 3. Product separation chamber; 31. Filter screen;

[0061] 4. Furnace; 41. Ammonia injection unit; 42. SCR flue gas denitrification unit; 43. Air preheater; 44. Bag filter / electrostatic precipitator; 45. Desulfurization tower.

[0062] 5. Chimney, 6. Oxygen, 7. Cold air, 8. Flue gas, 9. Flue gas with reduced carbon dioxide. Detailed Implementation

[0063] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0064] In the description of this invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0065] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0066] The following papers are referenced in this invention:

[0067] [1] Wu Yutao. Study on the performance of hydrophilic modified plastic packing for carbon capture and absorption towers [D]. Zhejiang University, 2022. DOI:10.27461 / d.cnki.gzjdx.2022.001514.

[0068] The above-described embodiments will be described in more detail below with reference to specific examples.

[0069] Example

[0070] See Figures 1 to 6 This embodiment provides a carbon dioxide capture and solid carbon generation system based on a cryogenic liquid alloy, including an absorption subsystem 1, an electrochemical reaction subsystem 2, and a product separation chamber 3.

[0071] The absorption subsystem 1 includes an absorption tower 11, with an inlet pipe 112 at its lower end for receiving flue gas 8 from a coal-fired power plant. An inlet pipe 15 is located at the upper end of the absorption tower 11, with its other end connected to a product separation chamber 3.

[0072] The system contains a circulating organic solution, and the inlet pipe 15 is used to receive the organic solution, which absorbs carbon dioxide from the flue gas 8 within the absorption tower 11.

[0073] The absorption tower 11 is provided with a liquid outlet 114 at its bottom end, and a liquid outlet pipe 115 is connected to the liquid outlet 114. The other end of the liquid outlet pipe 115 is connected to the electrochemical reaction subsystem 2. The liquid outlet 114 and the liquid outlet pipe 115 work together to introduce a carbon dioxide-rich organic solution into the electrochemical reaction subsystem 2.

[0074] The electrochemical reaction subsystem 2 includes a liquid alloy 2234, which is used to reduce carbon dioxide into solid carbon.

[0075] The electrochemical reaction subsystem 2 is provided with a manifold 23 at one end, and the other end of the manifold 23 is connected to the product separation chamber 3. The manifold 23 is used to introduce the organic solution with reduced solid carbon and carbon dioxide into the product separation chamber 3.

[0076] In this embodiment, a gas distributor 113 is provided at one end of the air inlet pipe 112 inside the absorption tower 11, a liquid distributor 16 is provided below one end of the liquid inlet pipe 15 inside the absorption tower 11, and a demister 14 is provided above one end of the liquid inlet pipe 15 inside the absorption tower 11. The demister 14 is used to remove mist from the flue gas 9 with reduced carbon dioxide.

[0077] In this embodiment, the liquid distributor 16 is a tubular liquid distributor and the gas distributor 113 is an elongated orifice gas distributor. The tubular liquid distributor and the elongated orifice gas distributor enable the organic solution and flue gas to enter the absorption tower 11 more evenly, increasing the contact area between the two.

[0078] In this embodiment, a multi-layered packing 18 with the same structure is provided between the air inlet pipe 112 and the liquid inlet pipe 15. A packing pressure plate 17 is provided above and below the packing 18. The packing pressure plate 17 is used to press the packing 18 to prevent the packing 18 from loosening or jumping under the action of the fluid. The absorption tower 11 is provided with multiple manholes 19 for observing the packing.

[0079] In this embodiment, the packing material 18 is a modified plastic packing material. Stainless steel perforated plate corrugated packing is the main choice for carbon dioxide capture systems due to its excellent performance, but it is expensive. Inexpensive plastic packing materials offer advantages such as large porosity and throughput, low resistance, low energy consumption and operating costs, light weight, easy installation and removal, and reusability, which can reduce the cost of the packing material by up to 50%. To address the problems of poor surface hydrophilicity and low strength of plastic packing materials, the plastic packing material is modified. [1] It has great application prospects for carbon capture and absorption, and is more suitable as a distribution device for the dispersion of flue gas and organic solutions in this invention.

[0080] In this embodiment, a liquid redistributor 110 is provided between the two layers of packing 18 in the middle of the absorption tower 11, and an interstage cooler 111 is provided at the lower part of the liquid redistributor 110. The interstage cooler 111 is used to lower the temperature of part of the organic solution, thereby reducing the equilibrium partial pressure of carbon dioxide gas, enhancing the ability of the organic solution to carry carbon dioxide, and improving the absorption efficiency.

[0081] In this embodiment, the top of the absorption tower 11 is provided with an outlet 13, and an outlet pipe 12 is connected to the outlet 13. The outlet 13 is used to discharge flue gas 9 with reduced carbon dioxide. The other end of the outlet pipe 12 is connected to the chimney 5.

[0082] In this embodiment, the electrochemical reaction subsystem 2 further includes multiple sets of reaction devices 22, a distribution manifold 21, and an exhaust pipe 24. The distribution manifold 21 is connected to the liquid outlet pipe 115 and is used to introduce carbon dioxide-rich organic solutions into the multiple sets of reaction devices 22 respectively.

[0083] One end of the reaction device 22 is connected to the branch manifold 21, and the other end of the reaction device 22 is connected to the confluence manifold 23 through a branch pipe. The exhaust pipe 24 is located on the branch pipe and is used to discharge the oxygen 6 generated by the reaction and the unreacted flue gas 8.

[0084] In this embodiment, multiple sets of the reaction devices 22 are stacked in parallel to enable large-scale production and application.

[0085] In this embodiment, the reaction device 22 includes a reaction vessel 221 and a power supply. The reaction vessel 221 is connected to the power supply. The reaction vessel 221 is provided with a flow channel 224. The wall of the flow channel 224 is provided with a counter electrode 222. The bottom of the reaction vessel 221 is provided with a liquid alloy electrode array (working electrode) 223.

[0086] The liquid alloy electrode array 223 includes conductive carbon fiber 2231, electrode substrate 2232, and capillary glass tube 2233. The electrode substrate 2232 is connected to the inside of the bottom end of the reaction vessel 221, and the capillary glass tube 2233 is fixed above the electrode substrate 2232.

[0087] The electrode substrate 2232 has a groove, and the capillary glass tube 2233 contains conductive carbon fiber 2231. The bottom end of the conductive carbon fiber 2231 is located in the groove of the electrode substrate 2232. The main wire of the conductive carbon fiber 2231 is connected to the negative terminal of the power supply. Liquid alloy 2234 is attached to the conductive carbon fiber 2231 at the end of the capillary glass tube 2233. By moving the capillary glass tube 2233 inside the liquid melt, liquid alloy droplets are attached to the conductive carbon fiber 2231. The high surface tension of the liquid alloy 2234 allows it to maintain its original shape during the electrochemical reaction. In this embodiment, the counter electrode 222 is an iron electrode.

[0088] In this embodiment, the top end of the conductive carbon fiber 2231 extends 0.5 cm beyond the top end of the capillary glass tube 2233, and the conductive carbon fiber 2231 is connected to the liquid alloy 2234. The conductive carbon fiber 2231 is used to charge the liquid alloy 2234.

[0089] In this embodiment, the product separation chamber 3 is equipped with a filter screen 31, which is used to separate solid carbon and organic solution with reduced carbon dioxide. The organic solution with reduced carbon dioxide is introduced into the absorption tower 11 through the inlet pipe 15 by a lean liquid pump.

[0090] Furthermore, this invention also provides a method for using a carbon dioxide capture and solid carbon generation system based on a cryogenic liquid alloy, the specific steps of which are as follows:

[0091] S1. Before the reaction, an organic solution is introduced into the system. The organic solution enters the absorption tower 11 through the liquid inlet pipe 15. The flue gas 8 from the coal-fired power plant enters the absorption tower 11 through the gas inlet pipe 112. The organic solution absorbs the carbon dioxide in the flue gas 8, resulting in an organic solution rich in carbon dioxide and flue gas 9 with reduced carbon dioxide.

[0092] S2. The carbon dioxide-rich organic solution obtained in step S1 is sequentially introduced into multiple reaction devices 22 through the liquid outlet pipe 115 and the diversion manifold 21. Under the action of external bias, carbon dioxide and liquid alloy 2234 undergo a reduction reaction on the surface of liquid alloy 2234 to generate solid carbon. At the same time, an oxygen evolution reaction occurs on the counter electrode 222 (anode side) to generate oxygen 6.

[0093] S3. The solid carbon obtained in step S2 and the organic solution with reduced carbon dioxide are introduced into the product separation chamber 3 and separated by the filter screen 31. The organic solution with reduced carbon dioxide is then introduced into the absorption tower 11 through the liquid inlet pipe 15.

[0094] In this embodiment, in step S1, the flue gas 8 from the coal-fired power plant is injected downwards into the absorption tower 11 through the inlet pipe 112 and gas distributor 113. It then flows upwards and contacts the organic solution sprayed down through the liquid inlet pipe 15 and liquid distributor 16, absorbing carbon dioxide from the flue gas 8. This results in an organic solution rich in carbon dioxide and flue gas 9 with reduced carbon dioxide levels. The flue gas 9 with reduced carbon dioxide levels passes through a demister 14 to remove mist before leaving the absorption tower 11 through the outlet pipe 12 and being discharged into the atmosphere through the chimney 5. In this embodiment, in step S1, the flue gas 8 from the coal-fired power plant undergoes pretreatment, including ammonia injection device 41 and SCR flue gas denitrification device 42 for denitrification, bag / electrostatic precipitator 44 for dust removal, and desulfurization in desulfurization tower 45.

[0095] In this embodiment, in step S1, the temperature of the flue gas 8 from the coal-fired power plant is 40 ℃-60 ℃, which provides a suitable temperature for the absorption and reaction of carbon dioxide.

[0096] In this embodiment, in step S1, the organic solution has an absorption rate of more than 90% for carbon dioxide in flue gas 8, and the organic solution is ethanolamine-methyldiethanolamine.

[0097] In this embodiment, the oxygen 6 obtained in step S2 is discharged through the exhaust pipe 24, collected and processed, and then introduced into the furnace 4 to promote the combustion of pulverized coal, thereby improving the combustion efficiency of the boiler and thus achieving continuous and stable operation of the entire system.

[0098] In this embodiment, in step S2, the adhesion rate of the liquid alloy 2234 on the capillary glass tube 2233 is higher than 95%, and the liquid alloy 2234 is a Bi-In-Sn based liquid alloy.

[0099] In this embodiment, in step S2, the external bias voltage is an external potential of -330 mV. vs CO2 / C.

[0100] In this embodiment, in step S2, the counter electrode 222 is immersed below the surface of the organic solution, and the liquid alloy electrode array 223 is immersed in the organic solution to form a circuit. The counter electrode 222 and the liquid alloy electrode array 223 do not contact each other, thus avoiding short circuits and ensuring the safe and efficient operation of the reaction system.

[0101] In this embodiment, in step S3, the solid carbon obtained in step S2 floats on the surface of the organic solution. The solid carbon obtained in step S2 and the organic solution with reduced carbon dioxide are introduced into the product separation chamber 3 through the manifold 23 and separated by the filter screen 31. The organic solution with reduced carbon dioxide is then introduced into the absorption tower 11 through the inlet pipe 15 under the action of the lean liquid pump.

[0102] like Figure 1 As shown, a carbon dioxide capture and solid carbon generation system is added before chimney 5, based on the existing power plant boiler flue gas emission system.

[0103] In this embodiment, the system costs 230 yuan to process one ton of carbon dioxide, which is nearly 50% lower than the cost of the CCS project (~450 yuan / ton (CO2)). The system's highest carbon conversion rate is 89%.

[0104] This system directly converts carbon dioxide into solid carbon materials, effectively fixing carbon dioxide. The low-cost nano-carbon products can be used in various fields such as catalysis, construction, and batteries, or sold as economic products, contributing to the development of energy storage and new energy technologies. Utilizing cryogenic liquid alloys to reduce carbon dioxide in flue gas from coal-fired power plants to solid carbon at near-room temperature achieves negative carbon emissions and further improves the production efficiency of coal-fired power plants. This is of great significance for energy conservation and carbon reduction in coal-fired power generating units, demonstrating significant demonstrative effects and promising prospects for widespread application.

[0105] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A carbon dioxide capture and solid carbon generation system based on cryogenic liquid alloys, characterized in that, It includes an absorption subsystem (1), an electrochemical reaction subsystem (2), and a product separation chamber (3). The absorption subsystem (1) includes an absorption tower (11), with an inlet pipe (112) at the lower end of the absorption tower (11) for receiving flue gas (8) from a coal-fired power plant. An inlet pipe (15) is located at the upper end of the absorption tower (11), with the other end of the inlet pipe (15) connected to the product separation chamber (3). The system contains a circulating organic solution, and the inlet pipe (15) is used to receive the organic solution, which absorbs carbon dioxide from the flue gas (8) in the absorption tower (11). The absorption tower (11) is provided with a liquid outlet (114) at the bottom end. The liquid outlet (114) is connected to a liquid outlet pipe (115). The other end of the liquid outlet pipe (115) is connected to the electrochemical reaction subsystem (2). The liquid outlet (114) and the liquid outlet pipe (115) work together to introduce the carbon dioxide-rich organic solution into the electrochemical reaction subsystem (2). The electrochemical reaction subsystem (2) includes a liquid alloy (2234) for reducing carbon dioxide to solid carbon. The electrochemical reaction subsystem (2) is provided with a manifold (23) at one end and the other end of the manifold (23) is connected to the product separation chamber (3). The manifold (23) is used to introduce the organic solution with reduced solid carbon and carbon dioxide into the product separation chamber (3). The electrochemical reaction subsystem (2) further includes multiple sets of reaction devices (22), a manifold (21), and an exhaust pipe (24). The manifold (21) is connected to the liquid outlet pipe (115) and is used to introduce carbon dioxide-rich organic solutions into the multiple sets of reaction devices (22). One end of the reaction device (22) is connected to the branch manifold (21), and the other end of the reaction device (22) is connected to the confluence manifold (23) through a branch pipe. The exhaust pipe (24) is located on the branch pipe and is used to discharge the oxygen (6) generated by the reaction and the unreacted flue gas (8). Multiple sets of the aforementioned reaction devices (22) are stacked in parallel. Each reaction device (22) includes a reaction vessel (221) and a power supply. The reaction vessel (221) is connected to the power supply. The reaction vessel (221) is provided with a flow channel (224). The wall of the flow channel (224) is provided with a counter electrode (222). The bottom of the reaction vessel (221) is provided with a liquid alloy electrode array (223). The liquid alloy electrode array (223) includes conductive carbon fiber (2231), an electrode substrate (2232), a capillary glass tube (2233), and a liquid alloy (2234). The electrode substrate (2232) is connected to the inside of the bottom of the reaction vessel (221), and the capillary glass tube (2233) is fixed above the electrode substrate (2232). The electrode substrate (2232) has a groove, and the capillary glass tube (2233) contains conductive carbon fiber (2231). The bottom end of the conductive carbon fiber (2231) is located in the groove of the electrode substrate (2232). The main bus of the conductive carbon fiber (2231) is connected to the negative terminal of the power supply. Liquid alloy (2234) is provided on the conductive carbon fiber (2231) at the end of the capillary glass tube (2233). By moving the capillary glass tube (2233), droplets of liquid alloy (2234) are attached to the conductive carbon fiber (2231). The high surface tension of the liquid alloy (2234) allows it to maintain its original shape during the electrochemical reaction.

2. The carbon dioxide capture and solid carbon generation system based on cryogenic liquid alloy according to claim 1, characterized in that, The gas inlet pipe (112) is provided with a gas distributor (113) at one end inside the absorption tower (11), the liquid inlet pipe (15) is provided with a liquid distributor (16) below one end inside the absorption tower (11), and the liquid inlet pipe (15) is provided with a demister (14) above one end inside the absorption tower (11). The demister (14) is used to remove mist from the flue gas (9) with reduced carbon dioxide. The air inlet pipe (112) and the liquid inlet pipe (15) are provided with a multi-layer packing (18) with the same structure. The packing (18) is provided with a packing pressure plate (17) above and below it. The packing pressure plate (17) is used to press the packing (18). The absorption tower (11) is provided with multiple manholes (19). The manholes (19) are used to observe the packing. A liquid redistributor (110) is provided between the two layers of packing (18) in the middle of the absorption tower (11), and an interstage cooler (111) is provided at the bottom of the liquid redistributor (110). The interstage cooler (111) is used to lower the temperature of part of the organic solution. The top of the absorption tower (11) is provided with an outlet (13), which is connected to an outlet pipe (12). The outlet (13) is used to discharge flue gas (9) with reduced carbon dioxide. The other end of the outlet pipe (12) is connected to the chimney (5).

3. The carbon dioxide capture and solid carbon generation system based on cryogenic liquid alloy according to claim 2, characterized in that, The liquid distributor (16) is a tube-groove type liquid distributor, the gas distributor (113) is a long-hole gas distributor, and the packing (18) is a modified plastic packing.

4. The carbon dioxide capture and solid carbon generation system based on cryogenic liquid alloy according to claim 1, characterized in that, The counter electrode (222) is an iron electrode; The conductive carbon fiber (2231) extends 0.3 to 0.8 cm from the top of the capillary glass tube (2233). The conductive carbon fiber (2231) is connected to the liquid alloy (2234). The conductive carbon fiber (2231) is used to charge the liquid alloy (2234).

5. The carbon dioxide capture and solid carbon generation system based on cryogenic liquid alloy according to claim 1, characterized in that, The product separation chamber (3) is equipped with a filter screen (31), which is used to separate solid carbon and organic solution with reduced carbon dioxide. The organic solution with reduced carbon dioxide is introduced into the absorption tower (11) through the inlet pipe (15).

6. A method of using the carbon dioxide capture and solid carbon generation system based on cryogenic liquid alloys as described in any one of claims 1-5, characterized in that, The specific steps are as follows: S1. Before the reaction, an organic solution is introduced into the system. The organic solution is introduced into the absorption tower (11) through the liquid inlet pipe (15). The flue gas (8) of the coal-fired power plant is introduced into the absorption tower (11) through the gas inlet pipe (112). The organic solution absorbs the carbon dioxide in the flue gas (8) to obtain an organic solution rich in carbon dioxide and flue gas (9) with reduced carbon dioxide. S2. The carbon dioxide-rich organic solution obtained in step S1 is sequentially introduced into multiple reaction devices (22) through the liquid outlet pipe (115) and the diversion manifold (21). Under the action of external bias, carbon dioxide and liquid alloy (2234) undergo a reduction reaction on the surface of liquid alloy (2234) to generate solid carbon, and at the same time, an oxygen evolution reaction occurs on the counter electrode (222) to generate oxygen (6). S3. The solid carbon obtained in step S2 and the organic solution with reduced carbon dioxide are introduced into the product separation chamber (3) and separated by the filter screen (31). The organic solution with reduced carbon dioxide is then introduced into the absorption tower (11) through the liquid inlet pipe (15).

7. The method of using the carbon dioxide capture and solid carbon generation system based on a cryogenic liquid alloy according to claim 6, characterized in that, In step S1, the flue gas (8) from the coal-fired power plant is sprayed downwards through the inlet pipe (112) and gas distributor (113) into the absorption tower (11). Then, it flows upwards and comes into contact with the organic solution sprayed down through the liquid inlet pipe (15) and liquid distributor (16). The organic solution is sprayed down through the liquid inlet pipe (15) and carbon dioxide is absorbed from the flue gas (8), resulting in an organic solution rich in carbon dioxide and flue gas (9) with reduced carbon dioxide. The flue gas (9) with reduced carbon dioxide is then de-misted by the demister (14) and leaves the absorption tower (11) through the outlet pipe (12) and is discharged into the atmosphere through the chimney (5). In step S1, the flue gas (8) of the coal-fired power plant undergoes pretreatment for denitrification, dust removal, and desulfurization. In step S1, the temperature of the flue gas (8) from the coal-fired power plant is 40℃-60℃. In step S1, the organic solution has an absorption rate of more than 90% for carbon dioxide in the flue gas (8); The oxygen (6) obtained in step S2 is discharged through the exhaust pipe (24), and after collection and treatment, it is introduced into the furnace (4) to promote the combustion of pulverized coal. In step S2, the adhesion rate of the liquid alloy (2234) to the capillary glass tube (2233) is higher than 95%. In step S2, the external bias voltage is an external potential, which is -330mV vs. CO2 / C; In step S2, the counter electrode (222) is immersed below the surface of the organic solution, and the liquid alloy electrode array (223) is submerged in the organic solution to form a circuit. The counter electrode (222) and the liquid alloy electrode array (223) do not contact each other. In step S3, the solid carbon obtained in step S2 floats on the surface of the organic solution. The solid carbon obtained in step S2 and the organic solution with reduced carbon dioxide are introduced into the product separation chamber (3) through the manifold (23). After being separated by the filter screen (31), the organic solution with reduced carbon dioxide is introduced into the absorption tower (11) through the inlet pipe (15) under the action of the lean liquid pump.

8. The method of using the carbon dioxide capture and solid carbon generation system based on a cryogenic liquid alloy according to claim 7, characterized in that, The organic solution is ethanolamine-methyldiethanolamine; The liquid alloy (2234) is a Bi-In-Sn based liquid alloy.

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