System and method for sequestering co 2 in air

Abstract

A system and method for sequestering CO2 in air. The system comprises a reactor body (1), wherein a gas distributor (6), one or more circulating material nozzles (7) and one or more fresh material nozzles (9) are sequentially arranged inside the reactor body (1) from bottom to top, the fresh material nozzles (9) are in communication with a fresh material storage tank (12) by means of feeding pipes, the circulating material nozzles (7) are in communication with the reactor body (1) by means of circulating pipes, a plurality of porous deflection baffles (4) are arranged inside the reactor body (1) at intervals in a \staggered manner in a height direction, fan blades (8) are arranged below the porous deflection baffles (4) in a staggered manner, and a gas inlet (5) and a gas outlet (2) are respectively provided at the bottom and the top of the reactor body (1). A better gas-solid-liquid three-phase mixing effect can be achieved, the absorption utilization rate of low-concentration CO2 and the utilization rate of calcium-containing substances or magnesium-containing substances can be increased, and moreover, the mixing effect of carbonate crystal nucleus can be enhanced, such that the particle size of a generated carbonate product is more uniform.

Description

A system and method for fixing CO2 in air This application claims priority to the Chinese patent application filed with the Patent Office of China on November 29, 2023, with application number 202311618168.4 and invention name “A system and method for fixing CO2 in the air”, the entire contents of which are incorporated by reference into this application. Technical Field

[0001] The present invention relates to the field of carbon neutrality technology, and in particular to a system and method for fixing CO2 in the air. Background Art

[0002] Excessive CO2 emissions will not only lead to climate change, but also affect biodiversity and the stability of ecosystems. Many plant and animal species are very sensitive to climate change. Extreme climate events such as global warming and drought can lead to biological extinction and ecosystem damage. Among anthropogenic CO2 gas emissions, ground point source emissions account for the highest proportion. Typical point source emissions mainly include industrial point source emissions such as fixed point sources in key industries such as thermal power, steel, petrochemicals, and chemicals, as well as elevated point sources. In addition, non-traditional point source emissions, including ground transportation, urban catering, waste disposal industry landfills, sewage treatment processes, and agriculture, forestry, animal husbandry, etc., cannot be ignored. Such non-traditional point source emissions are characterized by wide dispersion, large quantity, and difficulty in collection, and they can often only be allowed to be discharged into the atmosphere.

[0003] As one of the fundamental industrial elements of the national economy, industrial gases are playing an increasingly important role in the national economy. Air separation units (ASUs) are essential core facilities within the industrial gas industry. ASUs use air as a raw material, converting it into liquids at low temperatures. The distillation process then separates inert gases such as oxygen, nitrogen, and argon. ASUs primarily consist of eight systems: compression, purification, refrigeration, heat exchange, distillation, product delivery, liquid storage, and control. The ASU process follows: compressed air generated by an air compressor passes through a molecular sieve (purification system) to remove impurities such as moisture, carbon dioxide, and hydrocarbons. A portion of the compressed air is fed into the upper portion of a distillation column, while the remaining portion is cooled by an expander and fed back into the column. Heat exchange within the distillation column produces high-purity nitrogen and other gases at the top, while high-purity oxygen is obtained at the base.

[0004] At present, the impurities such as moisture, carbon dioxide, hydrocarbons, etc. removed by the molecular sieve (purification system) of the air separation equipment are directly discharged by blowing with dirty nitrogen gas, which is not conducive to achieving carbon emission reduction and waste gas recovery and reuse.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a system and method for fixing CO2 in the air, which can not only improve the absorption and utilization rate of low-concentration CO2 and the utilization rate of calcium-containing substances or magnesium-containing substances, but also enhance the mixing effect of carbonate crystal nuclei, making the particle size of the generated carbonate product more uniform.

[0007] The present invention provides a system for fixing CO2 in the air, comprising a reactor body, wherein a gas distributor, one or more circulating material nozzles and one or more fresh material nozzles are sequentially arranged inside the reactor body from bottom to top, the fresh material nozzles are connected to a fresh material storage tank via a feeding pipe, and the circulating material nozzles are connected to the reactor body via a circulating pipe, a plurality of porous deflection baffles are staggeredly arranged at intervals along the height direction inside the reactor body, fan blades are staggeredly arranged below the porous deflection baffles, and a gas inlet and a gas outlet are respectively provided at the bottom and top of the reactor body.

[0008] Furthermore, a demister and a flushing water nozzle are provided inside the reactor body. The demister is located above the fresh material nozzle, and the flushing water nozzle is located above the demister. The flushing water nozzle is connected to the flushing water storage tank through a flushing pipe.

[0009] Furthermore, multiple fresh material nozzles and multiple circulating material nozzles are provided inside the reactor body, and the multiple fresh material nozzles and multiple circulating material nozzles are staggered and arranged at intervals along the height direction of the reactor body, and the number of fresh material nozzles is greater than the number of circulating material nozzles.

[0010] Furthermore, the porous baffle is tilted downward, and the angle between the porous baffle and the reactor body is less than 60 degrees. The porous baffle has fish-scale holes with a diameter of 5mm×10mm, an opening height of 2mm, and an opening rate of 45-60%.

[0011] Furthermore, the fan blades rotate under the dual action of the air flow and the material flowing down through the porous deflection baffle.

[0012] The present invention also provides a method for fixing CO2 in the air, which is carried out using the above-mentioned system for fixing CO2 in the air. The method for fixing CO2 in the air includes: feeding a calcium-containing substance or a magnesium-containing substance into a reactor body through a fresh material nozzle, feeding a CO2-containing gas into the reactor body through a gas inlet, circulating the material inside the reactor body through a circulating material nozzle, and reacting the calcium-containing substance or the magnesium-containing substance with the CO2 in the CO2-containing gas to generate carbonate.

[0013] Furthermore, the calcium-containing substance is a calcium oxide or a calcium hydroxide, and the magnesium-containing substance is a magnesium oxide or a magnesium hydroxide; specifically, the calcium-containing substance can be carbide slag, steel slag, etc. In addition, the particle size of the calcium-containing substance or the magnesium-containing substance is 100-400 mesh, for example, 300-400 mesh.

[0014] Furthermore, the CO2-containing gas comes from an air separation and purification system; the volume concentration of CO2 in the CO2-containing gas is 0.1-5%.

[0015] Furthermore, the superficial gas velocity of the CO2-containing gas is 0.07-0.28 m / s.

[0016] The study found that when utilizing CO2-containing gas from the air separation and purification system, due to the low volume concentration of CO2 in the gas and the large gas volume, the use of traditional bubble towers, loop reactors and other equipment cannot achieve efficient absorption and utilization of CO2. This not only results in low utilization rates of CO2 and calcium / magnesium-containing materials, but also the uneven mixing of gas, liquid and solid phases results in a large particle size distribution range of the generated carbonate product, which is not conducive to actual production and application.

[0017] In response to the above problems, the present invention proposes a system and method for fixing CO2 in the air. By optimizing and controlling the structure and process of the system, porous deflection baffles and fan blades with fish-scale holes are set, and calcium / magnesium-containing substances form a liquid film on the surface of the porous deflection baffle and the fan blades. The CO2-containing gas is fully in contact with the liquid film of calcium / magnesium-containing substances during the rising process of the fish-scale holes. At the same time, under the turbulent effect of the fan blades, the CO2-containing gas is evenly distributed, and the gas-solid-liquid three-phase mixing effect is enhanced; in addition, by adopting a step-by-step countercurrent absorption operation mode, the CO2-containing gas is in countercurrent contact with the circulating material spray and the fresh material spray in turn, which can achieve efficient and sufficient absorption of ultra-low concentration CO2, which not only improves the absorption utilization rate of low-concentration CO2 and the utilization rate of calcium-containing substances or magnesium-containing substances, but also can enhance the uniform distribution of CO2 gas and the mixing effect of carbonate crystal nuclei, so that the particle size of the generated carbonate product is more uniform.

[0018] The system for fixing CO2 in the air of the present invention has a simple structure, an easy-to-control operation process, and is convenient for engineering scale-up and industrial production. The system uses impurity waste gas such as moisture, carbon dioxide, hydrocarbons, etc. removed by molecular sieve (purification system) in the air separation equipment as mineralization raw gas, and utilizes calcium-containing substances or magnesium-containing substances to react with CO2 in the mineralization raw gas to generate carbonate, thereby achieving the purpose of permanently fixing CO2 in the air, realizing carbon emission reduction and waste gas recycling and reuse, and at the same time making the particle size of the carbonate product more uniform, thereby improving the quality of the carbonate product. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] FIG1 is a schematic diagram of the structure of a system for fixing CO2 in air;

[0021] FIG2 is a particle size distribution diagram of the calcium carbonate product of Example 2;

[0022] FIG3 is a particle size distribution diagram of the calcium carbonate product of Reference Example 5;

[0023] FIG4 is a particle size distribution diagram of the calcium carbonate product of Reference Example 6.

[0024] Description of reference numerals:

[0025] 1: Reactor body; 2: Gas outlet; 3: Flushing water nozzle; 4: Porous baffle; 5: Gas inlet; 6: Gas distributor; 7: Circulating material nozzle; 8: Fan blade; 9: Fresh material nozzle; 10: Defoamer; 11: Circulating material storage tank; 12: Fresh material storage tank; 13: Flushing water storage tank. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular also includes the plural. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Example 1

[0030] As shown in Figure 1, the system for fixing CO2 in the air of this embodiment includes a reactor body 1, and a gas distributor 6, one or more circulating material nozzles 7 and one or more fresh material nozzles 9 are arranged in sequence from bottom to top inside the reactor body 1. The fresh material nozzle 9 is connected to the fresh material storage tank 12 through a feeding pipe, and the circulating material nozzle 7 is connected to the circulating slurry storage tank 11 through a circulation pipe. A plurality of porous deflection baffles 4 are arranged at intervals and staggered along the height direction inside the reactor body 1, and fan blades 8 are arranged staggered below the porous deflection baffles 4. A gas inlet 5 and a gas outlet 2 are respectively provided at the bottom and top of the reactor body 1.

[0031] The reactor body 1 is the place where calcium-containing substances or magnesium-containing substances react with CO2 in the CO2-containing gas; there are no strict restrictions on the shape and size of the reactor body 1, which can be reasonably set according to the actual CO2 processing capacity. The shape of the reactor body 1 can be cylindrical.

[0032] The fresh material nozzle 9 is mainly used to deliver the fresh material (calcium-containing material or magnesium-containing material) stored in the fresh material storage tank 12 to the interior of the reactor body 1 through the feeding pipe. The fresh material nozzles 9 can be staggered and arranged at intervals above the interior of the reactor body 1 along the height direction of the reactor body 1.

[0033] The circulating material nozzle 7 is mainly used to circulate the material inside the reactor body 1. A circulating material storage tank 11 can be set to store the circulating material. Circulating the material inside the reactor body 1 is not only beneficial to improving the utilization rate of calcium-containing substances or magnesium-containing substances, but also beneficial to inhibiting the disordered growth of the crystal nuclei of the carbonate product, strengthening the mixing effect of the carbonate crystal nuclei, and making the particle size of the generated carbonate product more uniform. The circulating material nozzle 7 can be staggered and arranged at intervals along the height direction of the reactor body 1 at the bottom of the reactor body 1. At this time, the setting position of the fresh material nozzle 9 is located above the circulating material nozzle 7. In order to further improve the absorption rate of CO2, the number of fresh material nozzles 9 can be set greater than the number of circulating material nozzles 7, which not only ensures the absorption utilization rate of CO2 gas but also ensures the utilization rate of calcium-containing substances or magnesium-containing substances.

[0034] The arrangement of the gas distributor 6 and multiple porous baffles 4 can better achieve a three-phase mixing effect for gas, solid, and liquid. There is no strict limit on the number of porous baffles 4 provided. In particular, the porous baffles 4 are arranged at a downward angle, with the angle between the porous baffles 4 and the reactor body 1 being less than 60 degrees, so that calcium- or magnesium-containing substances can flow down quickly. Furthermore, the porous baffles 4 can be interspersed with the multiple fresh material nozzles 9 and the multiple recirculating material nozzles 7, with at least one porous baffle 4 interspersed below each fresh material nozzle 9 and recirculating material nozzle 7.

[0035] The porous baffle 4 has fish-scale holes with a pore size of 5mm×10mm, an opening height of 2mm, and an opening rate of 45-60%, so that calcium / magnesium-containing substances can form a liquid film on the surface of the porous baffle, while not hindering the CO2-containing gas from fully contacting the calcium / magnesium-containing liquid film during the rising process through the fish-scale holes.

[0036] Fan blades 8 are staggeredly arranged below each porous baffle 4. The fan blades 8 are fixed to the reactor body 1 through support rods. The fan blades 8 are arranged below the outlet end of the porous baffle 4. The fan blades 8 rotate under the dual action of the rising airflow and the material flowing down through the porous baffle 4, thereby achieving uniform distribution of the CO2-containing gas under the action of turbulence.

[0037] A gas inlet 5 and a gas outlet 2 for gas inlet and outlet are respectively provided at the bottom and top of the reactor body 1; CO2 detection sensors for monitoring the flow rate and CO2 concentration of the inlet and outlet raw gas can be respectively provided at the gas inlet 5 and the gas outlet 2.

[0038] In addition, a demister 10 and a flushing water nozzle 3 are provided inside the reactor body 1. The demister 10 is located above the fresh material nozzle 9, and the flushing water nozzle 3 is located above the demister 10. The flushing water nozzle 3 is connected to the flushing water storage tank 13 through a flushing pipe. The flushing water nozzle 3 can be used to clean solids and the like contained in the demister to prevent clogging of the demister.

[0039] When the above system is used to fix CO2 in the air, the calcium-containing substance or the magnesium-containing substance is fed into the reactor body 1 through the fresh material nozzle 9, and the CO2-containing gas is fed into the reactor body 1 through the gas inlet 5. The material in the reactor body 1 is circulated through the circulating material nozzle 7, and the calcium-containing substance or the magnesium-containing substance reacts with the CO2 in the CO2-containing gas to form carbonate.

[0040] There is no strict restriction on the calcium-containing substance or the magnesium-containing substance. The calcium-containing substance can be a calcium oxide or a calcium hydroxide. The calcium-containing substance or the magnesium-containing substance can be fed into the reactor body 1 through the fresh material nozzle 9 in the form of slurry.

[0041] The CO2-containing gas can come from the air separation and purification system; the flow rate of calcium-containing substances or magnesium-containing substances and circulating materials can be determined according to actual conditions.

[0042] In the system for fixing CO2 in air of this embodiment, the calcium-containing substance or the magnesium-containing substance contacts the CO2-containing gas through spraying and the following reaction occurs:

[0043] CaO(s)+CO2(g)=CaCO3↓(s)

[0044] Ca(OH)2(s)+CO2(g)=CaCO3↓(s)+H2O(l)

[0045] or

[0046] MgO(s)+CO2(g)=MgCO3↓(s)

[0047] Mg(OH)2(s)+CO2(g)=MgCO3↓(s)+H2O(l)

[0048] Example 2

[0049] The method for fixing CO2 in the air of this embodiment is carried out using the system of Example 1.

[0050] Specifically, the reactor body 1 is cylindrical, 4 meters high and 0.5 meters in diameter. There are two circulating material nozzles 7, with the lowest one located 0.4 meters from the bottom of the reactor body 1 and the spacing between adjacent circulating material nozzles 7 being 0.6 meters. There are three fresh material nozzles 9, with the lowest one located 1.6 meters from the bottom of the reactor body 1 and the spacing between adjacent fresh material nozzles 9 being 0.6 meters. A fan blade 8 is positioned 0.48 meters below each fresh material nozzle 9 and circulating material nozzle 7. The support rod of the fan blade 8 is 10 cm long and the diameter of the fan blade 8 is 20 cm. There are five blades in total. The angle between the porous baffle 4 and the reactor body 1 is 30 degrees. The porous baffle 4 is 35 cm long and 30 cm wide, and the pores are distributed in a fish-scale pattern with a diameter of 5 mm x 10 mm. The opening height is 2 mm, and the porosity is 50%. The demister 10 is 0.4 m away from the top of the reactor body 1 , and the flushing water nozzle 3 is 0.2 m away from the top of the reactor body 1 .

[0051] In this embodiment, the calcium-containing substance selected from carbide slag is used as the solid raw material for mineralization. The calcium oxide content in the carbide slag is 68.1%, and the particle size of the carbide slag is controlled at 300 mesh. The impurity waste gas such as moisture, carbon dioxide, hydrocarbons, etc. removed by the dirty nitrogen purge molecular sieve (purification system) in the air separation equipment is used as the mineralization raw gas (referred to as raw gas for short). The volume concentration of CO2 in the mineralization raw gas is measured to be 1.3%.

[0052] The raw gas is fed into the reactor body 1 through the gas inlet 5, and the gas velocity is controlled at 50m 3 / h (the superficial gas velocity is 0.085m / s). Fresh carbide slag slurry is fed into the reactor body 1 through the fresh material nozzle 9. The solid content of the fresh carbide slag slurry is 30%, and the flow rate is 9.54m 3 / h; The circulating material is fed into the reactor body 1 through the circulating material nozzle 7, and the flow rate of the circulating material is 38.18m 3 / h.

[0053] The raw gas is distributed through the gas distributor 6 and is in countercurrent contact with the circulating material spray. The CO2 in the raw gas is partially absorbed and then continues to rise and is in countercurrent contact with the fresh carbide slag slurry spray. The CO2 in the raw gas further reacts with the calcium oxide in the carbide slag to form calcium carbonate. The raw gas with CO2 removed continues to rise and is discharged from the reactor body 1 through the gas outlet 2 after the solid entrainment is removed by the demister 10.

[0054] The CO2 absorption efficiency η is calculated according to the following formula:

[0055] η=(V in ×C in -V out ×C out ) / (V in ×C in )

[0056] in:

[0057] V in is the inlet raw gas flow rate, m 3 / h;

[0058] C in is the carbon dioxide concentration of the inlet raw gas, vol%;

[0059] V out is the outlet raw gas flow rate, m 3 / h;

[0060] C out is the outlet raw gas carbon dioxide concentration, vol%.

[0061] The absorption utilization rate η of CO2 in the raw gas was measured and calculated to be 95.41%.

[0062] The particle size distribution of the generated calcium carbonate is shown in FIG2 ; FIG2 shows that the calcium carbonate of this embodiment has a D10 of 0.813 μm, a D50 of 2.056 μm, and a D90 of 5.125 μm.

[0063] The ratio of calcium oxide in the mineralized solid raw material carbide slag converted into calcium carbonate (ie, the utilization rate of calcium) is 93.85%.

[0064] Example 3

[0065] This embodiment is basically the same as Embodiment 2 except for the following differences.

[0066] The magnesium-containing material of this embodiment selects magnesium hydroxide as the mineralized solid raw material, the magnesium hydroxide content is 90%, the particle size is controlled at 100 mesh, and the impurity waste gas such as moisture, carbon dioxide, hydrocarbons, etc. removed by the dirty nitrogen purge molecular sieve (purification system) in the air separation equipment is used as the mineralized raw gas, and the volume concentration of CO2 in the mineralized raw gas is 3.5%; the gas velocity of the raw gas is controlled at 150m 3 / h (superficial gas velocity 0.21m / s), the solid content of fresh magnesium hydroxide slurry is 25%, and the flow rate is 22.56m 3 / h, the flow rate of circulating material is 90.26m 3 / h.

[0067] The absorption utilization rate η of CO2 in the raw gas was measured and calculated to be 93.27%, and the ratio of the mineralized solid raw material magnesium hydroxide converted into magnesium carbonate (ie, the utilization rate of magnesium) was 90.21%.

[0068] Comparative Example 1

[0069] The raw gas, carbide slag raw material, operating process and parameters, dosage, reactor size, etc. used in this comparative example are the same as those in Example 2, except that:

[0070] Experiment 1: Only all the porous baffles inside the reactor body of Example 2 were removed.

[0071] Experiment 2: Only all the fan blades inside the reactor body of Example 2 were removed.

[0072] All other operations were the same as in Example 2, and the experimental results are shown in Table 1.

[0073] Table 1 Effects of different reactor body internal structures on CO2 absorption

[0074]

[0075] Comparative Example 2

[0076] The raw gas, carbide slag raw material, dosage, reactor, etc. used in this comparative example are the same as those in Example 2, except that:

[0077] Experiment 3: The material is not circulated, and all the circulating material nozzles 7 are used to spray fresh calcium carbide slag material.

[0078] Experiment 4: 3 nozzles from the bottom of the reactor body spray circulating materials, and 2 nozzles spray fresh material calcium carbide slag (that is, the lower 3 nozzles are circulating material nozzles, and the upper 2 nozzles are fresh material nozzles).

[0079] All other operations were the same as in Example 2, and the experimental results are shown in Table 2.

[0080] Table 2 Effect of nozzle setting on CO2 absorption

[0081]

[0082] Comparative Example 3

[0083] The raw gas, carbide slag raw material, operating process and parameters, dosage, reactor size, etc. used in this comparative example are the same as those in Example 2, except that:

[0084] Experiment 5: The angle between the porous baffle and the reactor body is 70 degrees.

[0085] Experiment 6: The angle between the porous baffle and the reactor body is 80 degrees.

[0086] All other operations were the same as in Example 2, and the experimental results are shown in Table 3.

[0087] Table 3 Effect of porous baffle angle on CO2 absorption

[0088]

[0089] Comparative Example 4

[0090] The carbide slag raw material, operating procedures, and reactor used in this comparative example were the same as in Example 2, except that the amount of contaminated nitrogen gas used to purge the molecular sieve (air separation purification system) was controlled to obtain CO2 gas of varying volume concentrations. The hourly flow rate of CO2 was the same as in Example 2, and the experimental results are shown in Table 4.

[0091] Table 4 Effect of CO2 concentration on CO2 absorption

[0092]

[0093] Comparative Example 5

[0094] This comparative example uses a traditional bubble tower as a system for fixing CO2 in the air, wherein the reactor body has a height of 4m and a diameter of 0.5m, and the aspect ratio and shape are the same as those in Example 2.

[0095] The mineralized solid raw materials and mineralized raw gas selected in this comparative example are the same as those in Example 2. Fresh carbide slag slurry with a solid content of 30% is added to the bubble tower. The particle size of the carbide slag is controlled at 300 mesh. The impurity waste gas such as moisture, carbon dioxide, hydrocarbons, etc. removed by the dirty nitrogen purge molecular sieve (purification system) in the air separation equipment is used as the mineralized raw gas (referred to as raw gas). The volume concentration of CO2 in the mineralized raw gas is measured to be 1.3%. The mineralized raw gas is introduced into the carbide slag slurry in the bubble tower, and the gas velocity is controlled at 50m 3 / h.

[0096] The absorption utilization rate η of CO2 in the raw gas was measured and calculated to be 41.13%.

[0097] The particle size distribution of the generated calcium carbonate is shown in FIG3 ; FIG3 shows that the calcium carbonate D10 of this comparative example is 0.777 microns, D50 is 2.379 microns, and D90 is 25.95 microns.

[0098] The ratio of calcium oxide in the mineralized solid raw material carbide slag converted into calcium carbonate (ie, the utilization rate of calcium) is 57.28%.

[0099] Comparative Example 6

[0100] This control example uses a loop reactor as a system for fixing CO2 in the air, wherein the reactor body has a height of 4m and a diameter of 0.5m, and the aspect ratio and appearance are the same as those in Example 2. The inner diameter of the draft tube is 0.4m and the height is 3.3m.

[0101] The mineralized solid raw materials and mineralized raw gas selected in this comparative example are the same as those in Example 2. Fresh carbide slag slurry with a solid content of 30% is fed into the loop reactor. The particle size of the carbide slag is controlled at 300 meshes. The waste gas from the air separation unit, which has been purged with dirty nitrogen gas to remove impurities such as moisture, carbon dioxide, and hydrocarbons (purification system), is used as the mineralized raw gas (referred to as raw gas). The volume concentration of CO2 in the mineralized raw gas is measured to be 1.3%. The mineralized raw gas is fed into the carbide slag slurry in the bubble tower at a gas velocity of 50 m / s. 3 / h.

[0102] The absorption utilization rate η of CO2 in the raw gas was measured and calculated to be 53.24%.

[0103] The particle size distribution of the generated calcium carbonate is shown in FIG4 ; FIG4 shows that the calcium carbonate D10 of this comparative example is 0.736 microns, D50 is 1.921 microns, and D90 is 18.45 microns.

[0104] The ratio of calcium oxide in the mineralized solid raw material carbide slag converted into calcium carbonate (ie, the utilization rate of calcium) is 64.81%.

[0105] The above results show that:

[0106] In Control Example 1, the CO2 absorption utilization rate η and the calcium utilization rate when the fan blades are installed alone or the porous baffle is installed alone are much lower than when the porous baffle and fan blades are installed at the same time. This is because calcium-containing substances or magnesium-containing substances can form a liquid film on the surface of the porous baffle and fan blades through the porous baffle and fan blades with fish-scale holes. The CO2-containing gas is fully in contact with the calcium / magnesium-containing liquid film during the rising process of the fish-scale holes. At the same time, under the turbulent effect of the fan blades, the CO2-containing gas is evenly distributed, which is conducive to the mixing of the gas-solid-liquid three-phase, and is beneficial to the improvement of the CO2 absorption utilization rate η and the calcium utilization rate.

[0107] In reference example 2, when the material is not circulated and all nozzles are used to spray fresh carbide slag material, the absorption utilization rate η of CO2 increases, but because material circulation is not taken, the utilization rate of calcium is reduced, and the crystal nuclei of the calcium carbonate product grow disorderly, causing the particle size distribution to broaden. When the number of circulating material nozzle sprays is more than the number of fresh material nozzle sprays, the absorption utilization rate η of CO2 decreases, but the mixing effect of the calcium carbonate crystal nuclei in the circulating material is enhanced, the particle size distribution narrows, and the particle size is more uniform.

[0108] In Control Example 3, the angle between the porous deflection baffle and the reactor body is greater than 60 degrees, the calcium-containing or magnesium-containing substances cannot flow down quickly, the impact force on the fan blades is reduced, the gas-liquid mixing effect is reduced, and the CO2 absorption utilization rate η is reduced.

[0109] In Comparative Example 4, when the CO2 concentration is too low or too high, at the same CO2 flow rate, the low CO2 concentration leads to an increase in the CO2-containing gas flow rate, and the excessive superficial gas velocity leads to a decrease in the CO2 absorption utilization rate η. The high CO2 concentration leads to a decrease in the CO2-containing gas flow rate, which cannot break through the resistance of the porous baffle with fish-scale pores and cannot fully contact with the calcium / magnesium-containing liquid film, resulting in a decrease in the CO2 absorption utilization rate η.

[0110] In Control Examples 5 and 6, since the volume concentration of CO2 in the raw gas from the air separation and purification system is low, the use of traditional bubble towers or loop reactors cannot achieve sufficient mixing and contact of gas, liquid and solid under low concentration CO2, which not only results in low material utilization, but also makes the particle size of the generated carbonate product uneven.

[0111] In summary, the present invention optimizes and controls the structure and process of the system, sets a porous baffle and fan blade with fish-scale holes, and forms a liquid film of calcium-containing or magnesium-containing substances on the surface of the porous baffle and fan blade. The CO2-containing gas fully contacts the calcium-containing or magnesium-containing liquid film during the rising process of the fish-scale holes. At the same time, under the turbulent effect of the fan blade, the uniform distribution of the CO2-containing gas is achieved, and the gas-solid-liquid three-phase mixing effect is enhanced. In addition, by adopting a step-by-step countercurrent absorption operation mode, the CO2-containing gas is sequentially countercurrently contacted with the circulating material spray and the fresh material spray, which can achieve efficient and sufficient absorption of ultra-low concentration CO2, not only improving the absorption utilization rate of low-concentration CO2 and the utilization rate of calcium-containing or magnesium-containing substances, but also strengthening the uniform distribution of CO2 gas and the mixing effect of carbonate crystal nuclei, making the particle size of the generated carbonate product more uniform. It not only achieves the purpose of permanently fixing CO2 in the air, realizes carbon emission reduction and waste gas recycling and reuse, but also improves the quality of carbonate products.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for fixing CO2 in air, characterized in that: The invention comprises a reactor body, wherein a gas distributor, one or more circulating material nozzles and one or more fresh material nozzles are sequentially arranged inside the reactor body from bottom to top, the fresh material nozzle is connected with a fresh material storage tank through a feeding pipe, the circulating material nozzle is connected with the reactor body through a circulating pipe, a plurality of porous baffle plates are staggeredly arranged at intervals along the height direction inside the reactor body, fan blades are staggeredly arranged below the porous baffle plates, and a gas inlet and a gas outlet are respectively arranged at the bottom and the top of the reactor body; a plurality of fresh material nozzles and a plurality of circulating material nozzles are arranged inside the reactor body, the plurality of fresh material nozzles and the plurality of circulating material nozzles are staggeredly arranged at intervals along the height direction of the reactor body, and the number of fresh material nozzles is greater than the number of circulating material nozzles; the porous baffle plates are tilted downward, the angle between the porous baffle plates and the reactor body is less than 60 degrees, the porous baffle plates are provided with fish scale-shaped holes with an aperture of 5 mm×10 mm, the opening height is 2 mm, and the opening rate is 45-60%.

2. The system according to claim 1, characterized in that A demister and a flushing water nozzle are also provided inside the reactor body. The demister is located above the fresh material nozzle, and the flushing water nozzle is located above the demister. The flushing water nozzle is connected to the flushing water storage tank through a flushing pipe.

3. The system according to claim 1, characterized in that The fan blades rotate under the dual action of the airflow and the material flowing down through the porous baffle.

4. A method for fixing CO2 in air, characterized in that: The method of fixing CO2 in the air, which is carried out using the system described in any one of claims 1 to 3, comprises: feeding a calcium-containing substance or a magnesium-containing substance into a reactor body through a fresh material nozzle, feeding a CO2-containing gas into the reactor body through a gas inlet, circulating the material inside the reactor body through a circulating material nozzle, and reacting the calcium-containing substance or the magnesium-containing substance with CO2 in the CO2-containing gas to generate carbonate.

5. The method according to claim 4, characterized in that The calcium-containing substance is calcium-containing oxide or calcium-containing hydroxide, and the magnesium-containing substance is magnesium-containing oxide or magnesium-containing hydroxide; the particle size of the calcium-containing substance or the magnesium-containing substance is 100-400 meshes.

6. The method according to claim 4, characterized in that The CO2-containing gas comes from an air separation and purification system; the volume concentration of CO2 in the CO2-containing gas is 0.1-5%.

7. The method according to claim 4, characterized in that The empty tower gas velocity of CO2-containing gas is 0.07-0.28m / s.

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