Absorbent for carbon fixation and decarbonization, preparation method thereof, and carbon fixation and decarbonization system

Abstract

This invention relates to the field of solid waste and hazardous waste treatment technology, specifically to an absorbent for carbon fixation and decarbonization, its preparation method, and a carbon fixation and decarbonization system. The preparation method includes: S1, weighing hazardous waste raw materials according to mass proportions, and subjecting them to crushing and mixing pretreatment to form a mixture; S2, transporting the mixture to a pyrolysis calcination furnace in a certain disposal volume through a pyrolysis hopper, and subjecting it to pyrolysis calcination treatment; S3, slowly conveying the pyrolysis calcined material to a grinding hopper, while simultaneously using a spray quenching device to spray quench the pyrolysis calcined material, followed by ball milling to obtain a slurry; S4, conveying the slurry to a slurry mixing tank, adjusting the pH value of the slurry to not be lower than 10, and stirring evenly to form an absorbent for carbon fixation and decarbonization. Using this absorbent for carbon fixation and decarbonization to treat carbon dioxide can not only reduce the treatment cost of solid waste and hazardous waste and increase their utilization value, but also reduce the cost of carbon dioxide disposal.

Description

Technical Field

[0001] This invention relates to the field of solid waste and hazardous waste treatment technology, and in particular to an absorbent for carbon fixation and decarbonization, its preparation method, and a carbon fixation and decarbonization system. Background Technology

[0002] Carbon dioxide is one of the main causes of global warming. Capturing, utilizing, and storing emitted carbon dioxide is one of the most effective means to achieve large-scale carbon emission reduction and address climate change. Existing decarbonization and carbon sequestration methods mainly include chemical absorption, physical absorption, and physical adsorption. These methods involve high investment and energy consumption. Furthermore, they all require the use and consumption of large amounts of decarbonization agents. For example, chemical absorption typically uses MDEA and MEA as decarbonization agents, physical absorption typically uses PC, NHD, and methanol, and physical adsorption typically uses silica gel. This further increases the cost of decarbonization and carbon sequestration. Therefore, it is necessary to find a cheap and widely applicable decarbonization and carbon sequestration agent.

[0003] At the current stage of development, industrial hazardous waste (hereinafter referred to as hazardous waste) or general solid waste (hereinafter referred to as solid waste), after undergoing a series of strict harmless treatment processes, is usually backfilled and buried in specific waste disposal sites. While this traditional disposal method can effectively isolate harmful substances to a certain extent and avoid immediate harm to human society, it requires a large amount of land space resources, which is undoubtedly a heavy burden for today's society where land resources are increasingly scarce. More seriously, any oversights during the landfill process or leakage occurring over a long period of time due to natural processes can cause harmful substances to seep into the soil layer, and then, through the circulation of groundwater systems, cause serious pollution to nearby soil, groundwater, and other natural elements, and may even spread to wider areas through air currents. This pollution not only disrupts the balance of the ecological environment but also seriously threatens the health, safety, and quality of life of nearby residents, posing a significant challenge to the sustainable development of the natural environment and human society. To address this problem, researchers and environmental protection departments are constantly exploring more efficient and environmentally friendly methods for the disposal of solid and hazardous waste. Currently, conventional treatment methods for hazardous and solid waste mainly include solidification and mineralization. Solidification involves mixing solid or hazardous waste with a solidifying agent, encapsulating or fixing the waste within a solidified substrate, and then converting it into ordinary building materials. However, this method has relatively limited utilization value. Mineralization typically involves two methods: one is to react the solidified waste in an acidic gas environment to generate carbonates, but this process is inefficient; the other is to mix the solid waste with an acidic aqueous solution using a mixing device. However, since the mixing device is a mechanical device, the release of acidic gases during operation can cause corrosion. Furthermore, the insufficient sealing performance of the mixing device prevents the use of pressure to improve reaction efficiency. Additionally, when treating large quantities of hazardous and solid waste, the required mixing equipment is generally large, increasing treatment costs. Therefore, there is a need to explore a solid or hazardous waste treatment method that is highly efficient, low-cost, and has high utilization value.

[0004] This invention provides an absorbent for carbon fixation and decarbonization, its preparation method, and a carbon fixation and decarbonization system to solve the problems of high treatment costs, limited utilization value, and high costs of decarbonization and carbon fixation in existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide an absorbent for carbon fixation and decarbonization, its preparation method, and a carbon fixation and decarbonization system, so as to solve the problems of high treatment costs, limited utilization value, and high costs of decarbonization and carbon fixation in existing technologies.

[0006] The technical solution of this invention is: a method for preparing an absorbent for carbon fixation and decarbonization, comprising the following steps:

[0007] S1. Weigh out hazardous waste materials according to mass fractions, and sequentially crush and mix the weighed hazardous waste materials to form a mixture; the hazardous waste materials include alkaline hazardous waste materials, acidic hazardous waste materials, and hazardous waste materials with uncertain acidity or alkalinity; among the hazardous waste materials, the content of alkaline hazardous waste materials is greater than the content of acidic hazardous waste materials;

[0008] S2. The mixed materials are transported to the pyrolysis calcination furnace in a certain throughput through the pyrolysis hopper, and then subjected to pyrolysis and calcination treatment in the furnace; the throughput does not exceed 2.5 t / h.

[0009] S3. The pyrolysis and calcination material is slowly conveyed to the grinding hopper, and simultaneously sprayed and cooled by a spray cooling device set at the top of the grinding hopper. After that, the cooled material is conveyed to a ball mill for ball milling to ensure that the particle size of the cooled material does not exceed 5 mm. After ball milling, a slurry is obtained. The mixing ratio of the cooled material to water in the slurry is 1:(99-98) by weight.

[0010] S4. The slurry is transported to the slurry mixing tank, and fresh water is supplied to the slurry mixing tank. At the same time, the activated composite alkali solution stored in the alkali solution tank is transported to the slurry mixing tank through the dosing pump to adjust the pH value of the slurry to not be lower than 10. After that, the mixture is stirred evenly to form an absorbent for carbon fixation and decarbonization.

[0011] Preferably, the alkaline hazardous waste material is any one or more of aluminum ash, red mud, fly ash, waste drilling mud, calcium carbide slag, coal gangue, and ironmaking waste slag; the acidic hazardous waste material is any one or more of phosphogypsum slag, acid oil slag, and acid slag; the hazardous waste material with uncertain acidity or alkalinity is any one or more of fly ash, oil sludge, rock cuttings, and garbage; the garbage includes medical waste and domestic waste.

[0012] Preferably, the pyrolysis calcination treatment involves igniting natural gas and non-condensable steam with a burner, and indirectly heating the mixed materials through the high-temperature flue gas generated by the combustion of natural gas and non-condensable steam; during the pyrolysis calcination treatment, the temperature inside the pyrolysis calcination furnace is controlled within the range of 400-1200℃.

[0013] Preferably, the length of the pyrolysis calcining furnace is not less than 20m; the front end of the furnace body near the pyrolysis hopper is a low-temperature pyrolysis zone, and the rear end of the furnace body is a high-temperature calcining zone.

[0014] The pyrolysis and calcination treatment includes low-temperature pyrolysis treatment at the front end of the furnace body and high-temperature calcination treatment at the rear end of the furnace body; the treatment temperature of the low-temperature pyrolysis treatment is 400-480℃.

[0015] Preferably, the activated composite alkaline solution comprises, by mass percentage, 18-23% NaOH, 12-18% piperazine, 8-12% sodium silicate, 10-18% tetraethylenepentamine, and the remainder being fresh water.

[0016] This application also provides an absorbent for carbon fixation and decarbonization, which is prepared by the above method.

[0017] This application also provides a carbon fixation and decarbonization system, which includes a carbon dioxide absorption device connected to the output end of a flue gas conveying pump installed on a flue gas conveying pipeline or connected to a carbon dioxide aqueous solution tank, wherein the carbon dioxide absorption device is connected to the slurry mixing tank containing the absorbent for carbon fixation and decarbonization.

[0018] Preferably, when the carbon dioxide absorption device is connected to the carbon dioxide aqueous solution tank, the carbon dioxide absorption device includes a pipeline mixer, a solid-liquid separator, a gas-water separator, and a screw conveyor connected to the front end of the carbon dioxide aqueous solution tank.

[0019] The front end of the pipeline mixer is connected to the slurry mixing tank via a slurry pump; the rear end of the pipeline mixer is connected to the solid-liquid separator; the upper end of the solid-liquid separator is connected to the gas-water separator, and the bottom end is connected to the screw conveyor; the upper end of the gas-water separator is provided with a gas outlet, and the bottom end is provided with a liquid outlet.

[0020] Preferably, when the carbon dioxide absorption device is connected to the carbon dioxide aqueous solution tank, the carbon dioxide absorption device includes a solid-liquid separation hydrocyclone connected to the slurry mixing tank via a slurry pump, a high-alkalinity solid material hopper connected to the bottom of the solid-liquid separation hydrocyclone, and a twin-screw high-pressure reactor connected to the high-alkalinity solid material hopper; the twin-screw high-pressure reactor is horizontally arranged; the front end of the twin-screw high-pressure reactor is connected to the carbon dioxide aqueous solution tank via a pipeline; and the rear end of the twin-screw high-pressure reactor is provided with an exhaust port and a discharge port.

[0021] Preferably, when the carbon dioxide absorption device is connected to the output end of the flue gas conveying pump installed on the flue gas conveying pipeline, the carbon dioxide absorption device includes a desulfurization and decarbonization tower; the bottom end of the desulfurization and decarbonization tower is connected to the output end of the flue gas conveying pump installed on the flue gas conveying pipeline, and the upper end is connected to the slurry mixing tank through a slurry pump; the top of the desulfurization and decarbonization tower is provided with a gas outlet, and the bottom is provided with a solid outlet.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] This invention provides an absorbent for carbon fixation and decarbonization, its preparation method, and a carbon fixation and decarbonization system. The absorbent is prepared from solid waste or hazardous waste through mixing, pyrolysis, incineration, grinding, and other processes. It is then used in a carbon fixation and decarbonization system to treat carbon dioxide. This not only reduces the treatment costs of solid waste and hazardous waste and increases their utilization value, but also improves the efficiency of carbon dioxide absorption and reduces carbon dioxide disposal costs through a pipeline reaction system and extended pipelines. This invention solves the problems of high treatment costs, limited utilization value, and high decarbonization and carbon fixation costs in existing technologies. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0025] Figure 1 This is a schematic diagram of the carbon fixation and decarbonization system described in this invention;

[0026] The components include: 1. Pyrolysis hopper; 2. Pyrolysis calcining furnace; 3. Burner; 4. Grinding hopper; 5. Ball mill; 6. Spray quenching device; 7. Desulfurization and decarbonization tower; 71. Flue gas conveying pump; 8. Alkali tank; 81. Dosing pump; 9. Slurry mixing tank; 91. Slurry pump; 10. Solid-liquid separation hydrocyclone; 11. High-alkaline solid material hopper; 12. Carbon dioxide aqueous solution tank; 13. Twin-shaft spiral high-pressure reactor; 14. Solid-liquid separator; 15. Pipeline mixer; 16. Gas-water separator; 17. Carbon dioxide recovery compressor; 18. Screw conveyor. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific embodiments:

[0028] This application provides an absorbent for carbon fixation and decarbonization. This absorbent uses hazardous or solid waste as raw material, and through mixing, pyrolysis, incineration, and grinding, the hazardous or solid waste raw material undergoes a series of physicochemical reactions to form an excited-state, highly alkaline solid slurry, which is then used as an absorbent for decarbonization and carbon fixation. Pyrolysis involves using a high-temperature environment to cause the organic components in the waste to undergo thermal decomposition, transforming them into gaseous, liquid, and solid residues. Incineration involves completely burning the waste under high-temperature conditions, generating ash and flue gas. The main substances in the final ash include relatively stable compounds such as metal oxides and silicates. These metal oxides and silicates can undergo chemical reactions upon contact with water, forming alkaline substances or hydrolyzing to produce basic substances. Therefore, this characteristic of hazardous or solid waste provides the possibility for subsequent waste resource utilization; it can reduce environmental pollution while achieving waste recycling, promoting the harmonious development of the economy and the environment.

[0029] This application also provides a method for preparing the above-mentioned absorbent for carbon fixation and decarbonization, which specifically includes the following steps:

[0030] S1. Weigh out the hazardous waste materials according to the mass fraction, and sequentially crush and mix the weighed hazardous waste materials to form a mixture. The hazardous waste materials include any one or more of the following: alkaline hazardous waste materials, acidic hazardous waste materials, and hazardous waste materials with uncertain acidity or alkalinity. When the hazardous waste materials include both alkaline and acidic hazardous waste materials, or alkaline, acidic, and hazardous waste materials with uncertain acidity or alkalinity, the content of alkaline hazardous waste materials must be much greater than the content of acidic hazardous waste materials. When the hazardous waste materials are acidic hazardous waste materials or liquids, lime or alkaline substances are needed to adjust their pH value. Commonly used alkaline hazardous waste materials include aluminum ash, red mud, fly ash, waste drilling mud, carbide slag, coal gangue, iron smelting waste, etc.; commonly used acidic hazardous waste materials include phosphogypsum slag, acid oil slag, acid slag, etc.; commonly used hazardous waste materials with uncertain acidity or alkalinity include fly ash, oil sludge, rock cuttings, and garbage. Among them, the main components of fly ash include silicon dioxide, alumina, iron oxide, and calcium oxide. Its acidity or alkalinity depends on its chemical composition and mineral composition. When the content of silicates (such as silicon dioxide) and aluminates (such as alumina) in fly ash is high, fly ash is acidic; while when the content of calcium hydroxide (lime) in fly ash is high, fly ash is alkaline. In this application, both acidic and alkaline fly ash can be used as hazardous waste materials in the preparation of absorbents for carbon fixation and decarbonization. The acidity or alkalinity of rock fragments depends on their composition and source, and both acidic and alkaline rock fragments can be used as hazardous waste materials in this application, with alkaline rock fragments being preferred. The waste used in this application includes medical waste and domestic waste. The acidity or alkalinity of medical waste and domestic waste also depends on their main components. Adding waste during the preparation of absorbents for carbon fixation and decarbonization can increase the calorific value of solid and hazardous waste. It can also increase the non-condensable vapors generated during pyrolysis and circulate these vapors for combustion, thereby reducing natural gas consumption. The weighed solid hazardous waste raw materials need to be crushed first to control the particle size within the range of 2-3 cm. Then, the crushed hazardous waste raw materials are added together with other hazardous waste raw materials into a mixing container for pre-treatment. After uniform mixing, a mixture is formed.

[0031] S2. The mixed materials are transported to the pyrolysis calcining furnace 2 in a certain amount through the pyrolysis hopper 1, and pyrolysis and calcination are carried out in the pyrolysis calcining furnace 2; wherein the processing capacity does not exceed 2.5 tons / hour (t / h); and, if Figure 1As shown, the pyrolysis calcination furnace 2 is horizontally integrated with the combustion device, and the burner 3 is located at the bottom of the combustion device. The pyrolysis calcination process involves igniting the natural gas and non-condensable steam in the combustion device using the burner 3, and indirectly heating the mixed materials through the high-temperature flue gas generated by the combustion of natural gas and non-condensable steam. During the pyrolysis calcination process, the temperature inside the pyrolysis calcination furnace 2 needs to be controlled within the range of 400-1200℃, depending on the hazardous waste raw materials used. In this application, a pyrolysis calcination furnace 2 with a furnace body length of not less than 20m is typically selected. The diameter of the pyrolysis calcination furnace 2 is proportional to the processing capacity. For example, when the processing capacity is 1t / h, a pyrolysis calcination furnace 2 with a furnace body diameter of 1m is selected; when the processing capacity is 1.5t / h, a pyrolysis calcination furnace 2 with a furnace body diameter of 1.5m is selected. The front end of the furnace body of the pyrolysis calcination furnace 2, which is close to the pyrolysis hopper 1, is a low-temperature pyrolysis zone with a furnace body length of 8-12m. The rear end of the furnace body is a high-temperature calcination zone. The mixed material transported into the pyrolysis calcination furnace 2 is first subjected to low-temperature pyrolysis treatment at the front end of the furnace body, and the treatment temperature of the low-temperature pyrolysis treatment is 400-480℃. Then, it is transported from the front end of the furnace body to the rear end of the furnace body for high-temperature calcination treatment. The organic materials in the mixture will decompose and produce combustible non-condensable gases after high-temperature calcination. These non-condensable gases will circulate and burn in the combustion device, which can effectively reduce the amount of natural gas used and save the cost of handling the mixture. The inorganic materials in the mixture will decompose or form silicates with the silicon dioxide after high-temperature calcination.

[0032] S3. The pyrolysis and calcination material is slowly conveyed to the grinding hopper 4. Simultaneously, the pyrolysis and calcination material is rapidly cooled by a spray cooling device 6 installed at the top of the grinding hopper 4. After cooling, the material is conveyed to the ball mill 5 for ball milling to ensure the particle size of the cooled material does not exceed 5mm. After ball milling, a slurry is obtained. The length of the ball mill 5 is approximately 5m. The diameter of the ball mill 5 is proportional to its throughput; for example, when the throughput of the ball mill 5 is 1t / h, a diameter of 1m is selected. At a capacity of 2 t / h, a ball mill with a diameter of 2 m is selected; the throughput of ball mill 5 does not exceed 2.51 t / h; through the continuous rotation of ball mill 5, the steel balls in ball mill 5 continuously grind the cooled material, so that the particle size of the cooled material reaches less than 5 mm. Small particles can increase the contact area with carbon dioxide gas or carbon dioxide aqueous solution, thereby increasing the reaction rate with carbon dioxide gas or carbon dioxide aqueous solution; at the same time, in order to ensure that the slurry has good fluidity, the mixing ratio of solid material and water is 1:99-98 by weight.

[0033] S4. The slurry is transported to the slurry mixing tank 9, and fresh water is supplied to the slurry mixing tank 9. Simultaneously, the activated composite alkali solution stored in the alkali solution tank 8 is supplied to the slurry mixing tank 9 via the dosing pump 81 to adjust the pH value of the slurry. Afterwards, the mixture is stirred evenly to obtain the absorbent for carbon fixation and decarbonization. After the ground slurry is transported to the slurry mixing tank 9, the pH value of the slurry needs to be tested. When the pH value of the slurry is not lower than 10, it is not necessary to supply the activated composite alkali solution to the slurry mixing tank 9. Only when the pH value of the slurry is found to be lower than 10 does it need to be supplied to the slurry mixing tank 9 via the dosing pump 81 to adjust the pH value of the slurry and activate the slurry. The activated composite alkali solution, calculated by mass percentage, includes 18-23% N... The active compound alkali solution comprises 12-18% NaOH, 12-18% piperazine (PZ), 8-12% sodium silicate, 10-18% tetraethylenepentamine, and the remainder being fresh water. Further, the preferred active compound alkali solution includes 20% NaOH, 15% piperazine, 10% sodium silicate, and 15% tetraethylenepentamine. The main function of NaOH is to increase the pH of the slurry; the main function of piperazine is to synergistically absorb carbon dioxide with tetraethylenepentamine; and the main function of sodium silicate is to synergistically activate silicates with NaOH and promote their crystallization and solidification. When preparing the absorbent for carbon fixation and decarbonization, highly alkaline hazardous waste raw materials should be added as much as possible to ensure or increase the alkalinity of the slurry and reduce the amount of active compound alkali solution used.

[0034] This application also provides a carbon fixation and decarbonization system; the system includes a carbon dioxide absorption device connected to the output end of a flue gas conveying pump 71 installed on a flue gas conveying pipeline or to a carbon dioxide aqueous solution tank 12; the carbon dioxide absorption device is also connected to the slurry mixing tank 9 containing the absorbent for carbon fixation and decarbonization. The input end of the flue gas conveying pump 71 installed on the flue gas conveying pipeline is connected to a device that generates or stores flue gas, used to convey the flue gas to the desulfurization and decarbonization tower 7, where it contacts and reacts with the absorbent for decarbonization and carbon fixation; while the carbon dioxide aqueous solution tank 12 is connected to a carbon dioxide recovery and compression unit and a fresh water source via an airflow pipeline and a water flow pipeline, respectively; carbon dioxide gas recovered from other sources is processed by the carbon dioxide recovery and compression unit and then conveyed to the carbon dioxide aqueous solution tank 12, where it dissolves in the fresh water conveyed to the tank to form a carbon dioxide aqueous solution.

[0035] In this system, when the carbon dioxide absorption device is connected to the output end of the flue gas conveying pump 71 installed on the flue gas conveying pipeline, the carbon dioxide absorption device includes a desulfurization and decarbonization tower 7. The bottom end of the desulfurization and decarbonization tower 7 is connected to the output end of the flue gas conveying pump 71 installed on the flue gas conveying pipeline, and the upper end of the desulfurization and decarbonization tower 7 is connected to the slurry mixing tank 9 via a slurry pump 91. The top of the desulfurization and decarbonization tower 7 is provided with a gas outlet, which is connected to the desulfurization and decarbonization seawater venting area via a pipeline. The bottom of the desulfurization and decarbonization tower 7 is provided with a solid outlet, which is connected to the desulfurization and decarbonization slurry storage area via a pipeline. At this time, the carbon fixation and decarbonization system is equivalent to a traditional tower system. The absorbent for decarbonization and carbon fixation is directly transported to the desulfurization and decarbonization tower by the slurry pump, and comes into contact with the flue gas spray. This allows the acidic gases such as sulfur dioxide and carbon dioxide in the flue gas to react with the highly alkaline absorbent for decarbonization and carbon fixation. The reaction process is similar to that of traditional lime milk desulfurization.

[0036] When the carbon dioxide absorption device is connected to the carbon dioxide aqueous solution tank 12, the carbon dioxide absorption device includes a solid-liquid separation hydrocyclone 10 connected to the slurry mixing tank 9 via a slurry pump 91, a high-alkalinity solid material hopper 11 connected to the bottom of the solid-liquid separation hydrocyclone 10, and a twin-screw high-pressure reactor 13 connected to the high-alkalinity solid material hopper 11; and the twin-screw high-pressure reactor 13 is horizontally arranged; the front end of the twin-screw high-pressure reactor 13 is connected to the carbon dioxide aqueous solution tank 12 via a pipeline; and the rear end of the twin-screw high-pressure reactor 13 is provided with an exhaust port and a discharge port. At this point, the carbon fixation and decarbonization system is a twin-screw high-pressure reaction system. The absorbent for carbon fixation and decarbonization is pumped to the solid-liquid hydrocyclone 10 via a slurry pump 91. Solid-liquid separation occurs in the hydrocyclone 10. The highly alkaline solid material with a particle size of less than 5 micrometers obtained from the separation and concentration is discharged from the bottom of the hydrocyclone 10 and transported to the twin-screw high-pressure reactor 13. Simultaneously, the carbon dioxide aqueous solution stored in the carbon dioxide aqueous solution tank 12, dissolved in water at a pressure of 1 MPa, is transported to the twin-screw high-pressure reactor 13. In the twin-screw high-pressure reactor 13, the carbon dioxide is thoroughly mixed and mineralized with the highly alkaline solid material. The products of the mineralization reaction and the liquid are discharged from the outlet at the rear end of the twin-screw high-pressure reactor 13 for external disposal or to be used to produce carbon-fixed building materials. Unreacted carbon dioxide gas is recovered back to the carbon dioxide aqueous solution tank 12. Furthermore, valves are installed at both the inlet at the front end and the outlet at the rear end of the twin-screw high-pressure reactor 13 to shut down the equipment.

[0037] To improve reaction efficiency, it is necessary to control the opening of the valve at the exhaust port of the twin-screw high-pressure reactor to maintain the pressure inside the reactor and ensure that carbon dioxide remains in a dissolved state. This carbon fixation and decarbonization system mainly utilizes the alkalinity of solid and hazardous waste for decarbonization; the higher the alkalinity, the better the decarbonization effect. Alternatively, collected and purified carbon dioxide can be fixed using hazardous and solid waste, and the solid waste after carbon fixation can be used to produce green carbon-fixed building materials.

[0038] In addition, to improve the efficiency of the reaction and absorption of carbon dioxide by the absorbent for carbon fixation and decarbonization, and to reduce the cost of carbon dioxide disposal, this application also provides a pipeline reaction system for carbon fixation and decarbonization. Specifically, when the carbon dioxide absorption device is connected to the carbon dioxide aqueous solution tank 12, the carbon dioxide absorption device may also include a pipeline mixer 15, a solid-liquid separator 14, a gas-liquid separator 16, and a screw conveyor 18, all connected to the front end of the carbon dioxide aqueous solution tank 12. Furthermore, the front end of the pipeline mixer 15 is connected to a slurry mixing tank 9 via a slurry pump 91, which is used to deliver the absorbent for carbon fixation and decarbonization to the pipeline mixer 15 at a pressure of 1 MPa. The absorbent is then mixed with the carbon dioxide aqueous solution in the pipeline mixer 15, allowing the carbon dioxide gas in the carbon dioxide aqueous solution to react and be absorbed by the absorbent. Simultaneously, the contact time between carbon dioxide and the slurry can be extended by increasing the pipeline length, thereby improving the reaction efficiency. The pipeline is also cheaper to manufacture and easier to process, which helps to reduce the cost of decarbonization and carbon fixation. The rear end of the pipeline mixer 15 is connected to the solid-liquid separator 14, which is used to transport the product of the reaction between the carbon fixation and decarbonization absorbent and carbon dioxide, the unreacted carbon fixation and decarbonization absorbent, and the unreacted carbon dioxide aqueous solution to the solid-liquid separator 14, where separation is completed. The upper end of the solid-liquid separator 14 is connected to the gas-water separator 16, which is used to transport the separated carbon dioxide aqueous solution to the gas-water separator 16 for separation of the water phase and the gas phase. The upper end of the gas-water separator 16 is provided with a gas outlet, which is used to discharge the separated gas phase into the atmosphere or recover it into the carbon dioxide aqueous solution tank through the carbon dioxide recovery compressor 17. The bottom of the gas-water separator is provided with a liquid outlet, which is used to discharge the separated water phase and return it to the slurry mixing tank 9 for continued use or return it to the ball mill for continued slurry making. The bottom of the solid-liquid separator 14 is connected to a screw conveyor, which is used to transport the separated solids to the screw conveyor 18, and then discharge them for backfill disposal or make them into carbon fixation building materials.

[0039] Five different combinations of hazardous waste raw materials with varying proportions are listed below, and these materials are prepared into carbon fixation and decarbonization absorbents using the methods described above. The proportions of each component in the hazardous waste raw material combinations are calculated by mass. The specific combinations and proportions of the hazardous waste raw materials are shown in Table 1.

[0040] Table 1. Combinations of hazardous waste materials with different components and proportions

[0041] Components fly ash Aluminum ash Red mud Drilling mud Rock cuttings Contains sludge Phosphogypsum Rubbish Acidity and alkalinity Alkaline Alkaline Alkaline Alkaline uncertain uncertain acidic uncertain Combination 1 1 1 1 1 1 1 1 10 Combination 2 / / 1 1 1 5 1 5 Combination 3 1 1 / 1 1 5 1 2 Combination 4 1 1 1 1 1 / 1 8 Combination 5 1 1 5 / / / 1 8

[0042] The carbon fixation and decarbonization absorbents prepared by combining the above five groups of hazardous waste raw materials with different components and ratios were applied to the above-mentioned traditional tower for carbon fixation and decarbonization. The absorption rate of flue gas and acid gas in the absorption tower was designed to be 95%, and the flow rate of carbon fixation and decarbonization absorbent consumed to achieve this absorption rate is shown in Table 2.

[0043] combination Combination 1 Combination 1 Combination 2 Combination 2 Combination 5 Combination 5 pH 11 13 11 13 11 13 The designed absorption tower has a flue gas acid gas absorption rate of 95%. <![CDATA[1Nm 3 Smoke / 18.2m 3 Slurry <![CDATA[10Nm 3 Smoke / 13.5m 3 Slurry <![CDATA[1Nm 3 Flue gas / 17.9m 3 Slurry <![CDATA[1Nm 3 Flue gas / 14.4m 3 Slurry <![CDATA[1Nm 3 Smoke / 11.2m 3 Slurry <![CDATA[1Nm 3 Smoke / 9.1m 3 Slurry

[0044] As shown in Table 2, the higher the pH value of the absorbent used for carbon fixation and decarbonization, the more conducive it is to the absorption of acidic gases such as carbon dioxide. In the combination of hazardous waste raw materials, increasing the proportion of red mud also helps to absorb acidic gases such as carbon dioxide.

[0045] The pH value of the five absorbents for carbon fixation and decarbonization prepared from the five groups of hazardous waste raw materials with different components and ratios was adjusted to 11. Then, these five absorbents were applied to the above-mentioned twin-screw high-pressure reaction system, pipeline reaction system and traditional mechanical stirring reaction system respectively, and carbon dioxide aqueous solution was treated under the same parameter conditions. The average carbon dioxide escape rate of different reaction systems during the treatment of carbon dioxide aqueous solution was detected. The specific test results are shown in Table 3.

[0046] Table 3. Average carbon dioxide escape rate of the same reaction system

[0047] System Name Twin-screw high-pressure reaction system Traditional mechanical stirring reaction system Pipeline reaction system Average carbon dioxide escape rate 64% 91% 34.5%

[0048] As shown in Table 3, when using a pipeline reaction system and employing five different absorbents for carbon fixation and decarbonization to treat carbon dioxide aqueous solution, the average carbon dioxide escape rate is 34.5%, which is significantly lower than the average carbon dioxide escape rate when using a twin-screw high-pressure reaction system and a traditional mechanical stirring reaction system. This indicates that using a pipeline reaction system can significantly improve the efficiency of the reaction and absorption of carbon dioxide by the absorbents for carbon fixation and decarbonization, and reduce the cost of carbon dioxide treatment.

[0049] The above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

Claims

1. A method for preparing an absorbent for carbon fixation and decarbonization, characterized in that, Includes the following steps: S1. Weigh out hazardous waste materials according to the specified proportions, and sequentially crush and pre-treat the weighed hazardous waste materials to form a mixture. The hazardous waste materials include alkaline hazardous waste materials, acidic hazardous waste materials, and hazardous waste materials with uncertain acidity or alkalinity. Among the hazardous waste materials, the content of alkaline hazardous waste materials is greater than the content of acidic hazardous waste materials. The alkaline hazardous waste materials are any one or more of aluminum ash, red mud, fly ash, waste drilling mud, calcium carbide slag, coal gangue, and ironmaking waste slag. The acidic hazardous waste materials are any one or more of phosphogypsum slag and acid slag. The hazardous waste materials with uncertain acidity or alkalinity are any one or more of fly ash, oil sludge, rock cuttings, and garbage. The garbage includes medical waste and / or domestic waste. S2. The mixed materials are transported to a pyrolysis calcination furnace in a certain amount through a pyrolysis hopper for pyrolysis and calcination treatment; during the pyrolysis and calcination treatment, the temperature inside the pyrolysis calcination furnace is controlled within the range of 400-1200℃; the processing capacity does not exceed 2.5t / h; the furnace body length of the pyrolysis calcination furnace is not less than 20m; the front end of the furnace body near the pyrolysis hopper is a low-temperature pyrolysis zone, and the rear end of the furnace body is a high-temperature calcination zone; The pyrolysis calcination treatment includes low-temperature pyrolysis treatment at the front end of the furnace and high-temperature calcination treatment at the rear end of the furnace; the treatment temperature of the low-temperature pyrolysis treatment is 400-480℃. S3. The pyrolysis and calcination material is slowly conveyed to the grinding hopper, and simultaneously sprayed and cooled by a spray cooling device set at the top of the grinding hopper. After that, the cooled material is conveyed to a ball mill for ball milling to ensure that the particle size of the cooled material does not exceed 5 mm. After ball milling, a slurry is obtained. The mixing ratio of the cooled material to water in the slurry is 1:(99-98) by weight. S4. The slurry is transported to the slurry mixing tank, and fresh water is supplied to the slurry mixing tank. At the same time, the activated composite alkali solution stored in the alkali solution tank is transported to the slurry mixing tank through the dosing pump to adjust the pH value of the slurry to not be lower than 10. After that, it is stirred evenly to form an absorbent for carbon fixation and decarbonization. The activated composite alkaline solution comprises, by mass percentage, 18-23% NaOH, 12-18% piperazine, 8-12% sodium silicate, 10-18% tetraethylenepentamine, and the remainder being fresh water.

2. The method for preparing an absorbent for carbon fixation and decarbonization according to claim 1, characterized in that: The pyrolysis calcination process involves igniting natural gas and non-condensable steam with a burner, and then indirectly heating the mixture through the high-temperature flue gas generated by the combustion of natural gas and non-condensable steam.

3. An absorbent for carbon fixation and decarbonization, characterized in that: It is prepared using the preparation method described in claim 1 or 2.

4. A carbon fixation and decarbonization system, comprising a carbon dioxide absorption device connected to the output end of a flue gas conveying pump installed on a flue gas conveying pipeline or connected to a carbon dioxide aqueous solution tank, characterized in that, The carbon dioxide absorption device is connected to a slurry mixing tank containing the absorbent for carbon fixation and decarbonization as described in claim 3.

5. The carbon fixation and decarbonization system according to claim 4, characterized in that: When the carbon dioxide absorption device is connected to the carbon dioxide aqueous solution tank, the carbon dioxide absorption device includes a pipeline mixer, a solid-liquid separator, a gas-water separator, and a screw conveyor connected to the front end of the carbon dioxide aqueous solution tank. The front end of the pipeline mixer is connected to the slurry mixing tank via a slurry pump; the rear end of the pipeline mixer is connected to the solid-liquid separator; the upper end of the solid-liquid separator is connected to the gas-water separator, and the bottom end is connected to the screw conveyor; the upper end of the gas-water separator is provided with a gas outlet, and the bottom end is provided with a liquid outlet.

6. The carbon fixation and decarbonization system according to claim 4, characterized in that: When the carbon dioxide absorption device is connected to the carbon dioxide aqueous solution tank, the carbon dioxide absorption device includes a solid-liquid separation rotary device connected to the slurry mixing tank via a slurry pump, a high-alkalinity solid material hopper connected to the bottom of the solid-liquid separation rotary device, and a twin-screw high-pressure reactor connected to the high-alkalinity solid material hopper; the twin-screw high-pressure reactor is horizontally arranged; the front end of the twin-screw high-pressure reactor is connected to the carbon dioxide aqueous solution tank via a pipeline; and the rear end of the twin-screw high-pressure reactor is provided with an exhaust port and a discharge port.

7. The carbon fixation and decarbonization system according to claim 4, characterized in that: When the carbon dioxide absorption device is connected to the output end of the flue gas conveying pump installed on the flue gas conveying pipeline, the carbon dioxide absorption device includes a desulfurization and decarbonization tower; the bottom end of the desulfurization and decarbonization tower is connected to the output end of the flue gas conveying pump installed on the flue gas conveying pipeline, and the upper end is connected to the slurry mixing tank through a slurry pump; the top of the desulfurization and decarbonization tower is provided with a gas outlet, and the bottom is provided with a solid outlet.

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