Method for capturing CO2 by using high-temperature converter steel slag and biochar
Through the combination of steel slag with high-temperature converter and biochar, the reaction CO2+4C+2H2O=CH4+4CO is used to solve the problems of carbon dioxide emissions and high-temperature thermal energy waste in thermal power plants, and the capture of carbon dioxide and the recovery of heat are achieved, and the energy utilization efficiency and the utilization value of biochar are improved.
Patent Information
- Application Number
- CN202510563012.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-30
- Publication Date
- 2025-07-18
AI Technical Summary
In the prior art, the carbon dioxide emissions of thermal power plants are large and the energy consumption of the carbon dioxide capture process is high. The thermal energy of the steel slag of high-temperature converter is not fully utilized, resulting in energy waste.
The method of combining high-temperature converter steel slag and biochar is adopted to capture carbon dioxide and recover high-temperature heat by reacting CO2+4C+2H2O=CH4+4CO. The specific steps include collecting carbon dioxide gas, collecting high-temperature converter steel slag and biochar, and controlling reaction conditions such as temperature, pressure and steam flow.
It has achieved carbon dioxide capture and high-temperature heat recovery, reduced carbon emissions, broadened the field of biochar utilization, realized high-value recycling of waste, and improved the energy utilization efficiency of power plants.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of efficient utilization of high-temperature converter slag, and specifically to a method for capturing CO2 by using high-temperature converter slag and biochar. Background Art
[0002] Carbon emissions refer to the process of emitting greenhouse gases such as carbon dioxide into the atmosphere during human activities and natural processes. The increase in carbon emissions is one of the main reasons for global warming. Taking a thermal power plant as an example, during the thermal power generation process, heat energy is mainly generated by burning coal, and then a steam turbine is driven to generate electricity. Since coal has a high carbon content, a large amount of carbon dioxide will be generated when it burns with oxygen. For every 1 ton of standard coal burned, about 2.6 tons of carbon dioxide will be produced. If a large thermal power plant consumes millions or even tens of millions of tons of coal every year, its carbon dioxide emissions will be a very huge figure.
[0003] In order to reduce the carbon dioxide emissions of thermal power plants, the current measures are to adopt clean coal technology, carry out carbon capture and storage (CCS), etc. Carbon capture mainly uses the carbon dioxide in the soot to react with a certain substance, and then fixes and captures it. After capture, it usually needs to be stored, and the storage method generally adopts injection into depleted oil and gas fields and ocean storage methods.
[0004] However, capturing carbon dioxide requires complex chemical absorption (such as amine solvents) or physical separation technologies. This process will consume 20% - 30% of the energy output of the power plant, significantly reducing the power generation efficiency, and at the same time greatly increasing the operating cost (the cost of capturing per ton of CO2 is about $40 - $120). The temperature of the converter slag after it comes out of the furnace is very high, usually at 1600 - 1700 °C, and this part of the heat energy has not been fully utilized at present, resulting in a waste of energy. Summary of the Invention
[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method for capturing CO2 by using high-temperature converter slag and biochar, which can not only capture carbon dioxide but also recover the heat of the high-temperature converter slag.
[0006] In order to achieve the above object, the present invention is implemented by adopting the following technical solutions:
[0007] A method for capturing CO2 by using high-temperature converter slag and biochar specifically includes the following steps:
[0008] S1: Collect carbon dioxide gas, and after treatment, convert it into a carbon dioxide gas source;
[0009] S2: Collect high-temperature converter slag;
[0010] Pour the high-temperature molten steel slag produced after the converter steelmaking into a container, and collect the converter steel slag with a temperature higher than 1000 °C;
[0011] S3: Biochar collection;
[0012] Collect biochar raw materials, and dry the biochar raw materials at a temperature of 100-300 °C for 5-8 h;
[0013] After that, perform high-temperature pyrolysis, and crush the pyrolyzed biochar into carbon powder;
[0014] S4: Open a spout and a carbon powder inlet at the bottom of the high-temperature steel slag container. The spout is connected to a carbon dioxide gas source through a pipeline. Open a high-temperature steam injection inlet on the side wall of the high-temperature steel slag container, and open a gas collection pipeline at the top of the high-temperature steel slag collection container;
[0015] S5: Blow carbon dioxide from the bottom spout into the high-temperature steel slag container, inject carbon powder into the high-temperature steel slag container through the carbon powder inlet, and inject high-temperature steam into the high-temperature steel slag container through the high-temperature steam inlet;
[0016] S6: Complete the reaction in the high-temperature steel slag container: CO2 + 4C + 2H2O = CH4 + 4CO, the reaction temperature is greater than 700 °C, and the generated combustible gas is recovered through the gas collection pipeline.
[0017] Further, in S3, the pyrolysis temperature is controlled at 500-800 °C.
[0018] Further, in S3, before crushing the pyrolyzed biochar, quickly cool it to 20-30 °C at a cooling rate of 10-20 °C / s.
[0019] Further, in S3, crush the pyrolyzed biochar into carbon powder with a mesh size of 100-200.
[0020] Further, in S5, the bottom-blowing carbon dioxide gas pressure is controlled at 0.4-0.8 MPa.
[0021] Further, in S5, the injection amount of carbon powder is controlled at 10-50 kg / min;
[0022] Further, in S5, two high-temperature steam injection inlets are symmetrically opened in the middle of the side wall of the high-temperature steel slag container.
[0023] Further, in S5, the injection pressure of steam is controlled at 0.2-0.4 MPa, and the steam flow rate is controlled at 40-60 L / min.
[0024] Further, in S5, the temperature of the high-temperature steam is 200-600 °C.
[0025] Compared with the existing method, the beneficial effects of the present invention are:
[0026] 1. The temperature of converter steel slag after tapping is very high, usually at 1600 - 1700 °C, and this part of thermal energy has not been fully utilized at present, resulting in waste of energy. How to combine the high-temperature thermal energy of the converter with carbon dioxide has become a technical problem urgently to be solved in this field. The present invention utilizes the following reaction: CO2 + 4C + 2H2O = CH4 + 4CO. This reaction is an endothermic reaction and requires a temperature above 950 °C to occur through thermodynamic analysis. Based on this principle, the present invention combines carbon dioxide capture with high-temperature heat recovery organically. The present invention enables the high-efficient utilization of the heat of the high-temperature converter steel slag in the steel plant, simultaneously completes the capture of the greenhouse gas carbon dioxide, and broadens the utilization fields of biochars such as crop straws, peanut shells, and melon seed shells, thereby realizing the reduction of carbon dioxide emissions and the high-value recycling of waste.
[0027] 2. The present invention opens a spout and a carbon powder inlet at the bottom of the high-temperature steel slag container. The spout is communicated with a carbon dioxide gas source through a pipeline. A high-temperature steam inlet is opened on the side wall of the high-temperature steel slag container, and a gas collection pipeline is opened at the top of the high-temperature steel slag collection container. The deep coordination of the device and process of the present invention realizes the triangular optimization of technology, cost, and quality.
[0028] 3. The present invention controls the pyrolysis temperature at 500 - 800 °C. This temperature range ensures the full pyrolysis of biomass (complete decomposition of cellulose / hemicellulose), and at the same time avoids over-carbonization (graphitization at >800 °C leads to a decrease in activity). The biochar generated by medium-temperature pyrolysis has a relatively high specific surface area and active sites, which is conducive to the contact efficiency with CO2 / H2O in the subsequent gasification reaction.
[0029] 4. In order to facilitate the crushing of the pyrolyzed biochar, after pyrolysis, it is rapidly cooled to 20 - 30 °C at a rate of 10 - 20 °C / s. Rapid cooling can avoid pore collapse or surface passivation when the biochar cools slowly, and maintain high reaction activity.
[0030] 5. The present invention controls the bottom-blown carbon dioxide gas pressure at 0.4 - 0.8 MPa to strengthen the gas-solid reaction. Excessive pressure (>0.8 MPa) may cause excessive foaming of the molten slag, hindering the dispersion of carbon powder; the range of 0.4 - 0.8 MPa can optimize the viscosity of the molten slag and the bubble size, and increase the reaction surface area. Detailed implementation mode
[0031] The present invention discloses a method for capturing CO2 by using high-temperature converter steel slag and biochar. Those skilled in the art can draw on the content of this article and appropriately improve the process parameters to achieve it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are all considered to be included in the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously make changes, or appropriate changes and combinations, to the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.
[0032] A method for capturing CO2 by using high-temperature converter steel slag and biochar specifically includes the following steps:
[0033] 1. Carbon dioxide collection:
[0034] Collect the carbon dioxide gas generated in daily activities and natural processes.
[0035] 2. High-temperature converter steel slag collection:
[0036] Pour the high-temperature slag generated after steelmaking in the converter into a special heat-insulating or heatable container.
[0037] In order to enable CO2 to fully undergo the following reaction: CO2 + 4C + 2H2O = CH4 + 4CO, and the reaction temperature is greater than 700 °C, it is required that the temperature of the converter steel slag be higher than 1000 °C.
[0038] 3. Biochar collection:
[0039] Collect biochar raw materials such as straw, peanut shells, and melon seed shells generated in daily life and production.
[0040] In order to facilitate the generation of biochar, the collected biochar is dried. The biochar raw materials such as straw, peanut shells, and melon seed shells are dried at a temperature of 100 - 300 °C for 5 - 8 h to remove the moisture and bio-oil in the raw materials. Then it is loaded into a sealed pyrolysis container for high-temperature pyrolysis, and the pyrolysis temperature is controlled at 500 - 800 °C. In order to facilitate the crushing of the pyrolyzed biochar, after pyrolysis, it is quickly cooled to 20 - 30 °C at a rate of 10 - 20 °C / s. The pyrolyzed biochar is crushed into 100 - 200 mesh carbon powder.
[0041] 4. Open a bottom spray port at the bottom of the high-temperature steel slag collection container, and then connect it to the collected carbon dioxide gas source through a pipeline.
[0042] 5. Open a carbon powder inlet at the bottom spray port, control the bottom blowing gas pressure at 0.4 - 0.8 MPa, and control the carbon powder injection amount at 10 - 50 kg / min.
[0043] 6. There are 2 high-temperature steam injection inlets symmetrically arranged along the vertical axis in the middle of the side wall of the high-temperature steel slag collection container. The injection pressure of the steam is controlled at 0.2 - 0.4 MPa, the steam flow rate is controlled at 40 - 60 L / min, and the high-temperature steam is at 200 - 600 °C.
[0044] 7. A gas collection pipeline is opened at the top of the high-temperature steel slag collection container to recover the combustible gas generated by the high-temperature reaction.
[0045] Example 1: Capturing CO2 with 1600 °C steel slag and straw biochar.
[0046] The collected straw is dried. The straw biochar raw material is dried at 150 °C for 6 h to remove the moisture and bio-oil in the straw raw material.
[0047] Then it is loaded into a sealed pyrolysis container for high-temperature pyrolysis. The pyrolysis temperature is controlled at 600 °C. After pyrolysis, it is rapidly cooled to 25 °C at 10 - 20 °C / s. The pyrolyzed carbonaceous straw is crushed into 100-mesh carbon powder.
[0048] Collect 1600 °C high-temperature steel slag in a heat-insulating container. Open a bottom injection port at the bottom of the container and connect it to the collected carbon dioxide gas source through a pipeline.
[0049] And open a carbon powder inlet at the bottom injection port. The bottom blowing gas pressure is controlled at 0.6 MPa, and the carbon powder injection amount is controlled at 25 kg / min.
[0050] There are 2 high-temperature steam injection inlets symmetrically arranged in the middle of the side wall of the high-temperature steel slag collection container. The injection pressure of the steam is controlled at 0.5 MPa, and the steam flow rate is controlled at 50 L / min.
[0051] Complete the reaction CO2 + 4C + 2H2O = CH4 + 4CO, and recover the combustible gas generated by the high-temperature reaction through the top gas collection pipeline of the high-temperature steel slag collection container.
[0052] Example 2: Capturing CO2 with 1500 °C steel slag and peanut shell biochar
[0053] The collected straw is dried. The straw biochar raw material is dried at 250 °C for 6 h to remove the moisture and bio-oil in the peanut shell raw material.
[0054] Then it is loaded into a sealed pyrolysis container for high-temperature pyrolysis. The pyrolysis temperature is controlled at 700 °C. After pyrolysis, it is rapidly cooled to 30 °C at 10 - 20 °C / s. The pyrolyzed carbonaceous peanut shell is crushed into 150-mesh carbon powder.
[0055] Collect the high-temperature steel slag at 1500 °C in a heat-insulated container, and open a bottom nozzle at the bottom of the container to connect it to the collected carbon dioxide gas source through a pipeline.
[0056] And open a carbon powder inlet at the bottom nozzle. Control the bottom-blowing gas pressure at 0.7 MPa and the carbon powder injection amount at 30 kg / min. Symmetrically open 2 high-temperature steam inlets in the middle of the side wall of the high-temperature steel slag collection container. Control the steam injection pressure at 0.6 MPa and the steam flow rate at 45 L / min.
[0057] Complete the reaction CO2 + 4C + 2H2O = CH4 + 4CO, and recover the combustible gas generated by the high-temperature reaction through the gas collection pipeline at the top of the high-temperature steel slag collection container.
[0058] The present invention utilizes the following reaction: CO2 + 4C + 2H2O = CH4 + 4CO. This reaction is an endothermic reaction, and through thermodynamic analysis, this reaction needs to occur above 950 °C. Based on this principle, the present invention combines carbon dioxide capture and high-temperature heat recovery organically. The present invention enables the high-efficient utilization of the heat of the high-temperature converter steel slag in the steel mill, while completing the capture of the greenhouse gas carbon dioxide, and broadening the utilization fields of biochar such as crop straws, peanut shells, and melon seeds, thereby realizing the reduction of carbon dioxide emissions and the high-value recycling of waste.
[0059] The present invention realizes the capture of CO2, reduces carbon emissions; realizes the heat recovery of high-temperature converter steel slag; realizes the recycling of carbon-containing biomass waste. Synergistic benefits: 1 + 1 + 1 > 3, technical integration advantages, multiple emission reduction effects, and industrial chain extension. The present invention through the "carbon reduction + energy conservation + recycling" triple mechanism not only solves the pain points of industrial emissions and resource waste, but also transforms the environmental protection pressure into economic benefits, achieving a win-win situation for the environment, enterprises, and society.
[0060] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.
Claims
1. A method for capturing CO2 using high-temperature converter steel slag and biochar, characterized in that Specifically, it includes the following steps: S1: Collect carbon dioxide gas and convert it into a carbon dioxide gas source after treatment; S2: Collect high-temperature converter slag; Pour the high-temperature molten converter slag generated after the converter steelmaking is completed into a container, and collect the converter slag with a temperature higher than 1000 °C; S3: Collect biochar; Collect biochar raw materials, dry the biochar raw materials at a temperature of 100 - 300 °C for 5 - 8 h; Then carry out high-temperature pyrolysis, and crush the pyrolyzed biochar into carbon powder; S4: Open a spout and a carbon powder inlet at the bottom of the high-temperature slag container. The spout is connected to the carbon dioxide gas source through a pipeline. Open a high-temperature steam inlet on the side wall of the high-temperature slag container, and open a gas collection pipeline at the top of the high-temperature slag container; S5: Blow carbon dioxide from the spout to the inside of the high-temperature slag container, spray carbon powder into the high-temperature slag container from the carbon powder inlet, and spray high-temperature steam into the high-temperature slag container from the high-temperature steam inlet; S6: Complete the reaction in the high-temperature slag container: CO2 + 4C + 2H2O = CH4 + 4CO, the reaction temperature is greater than 700 °C, and the generated combustible gas is recovered through the gas collection pipeline.
2. A method for capturing CO2 using high-temperature converter slag and biochar according to claim 1, wherein in S3, the pyrolysis temperature is controlled at 500 - 800 °C.
3. A method for capturing CO2 using high-temperature converter slag and biochar according to claim 1, wherein in S3, before the pyrolyzed biochar is crushed, it is quickly cooled to 20 - 30 °C at a cooling rate of 10 - 20 °C / s.
4. A method for capturing CO2 using high-temperature converter slag and biochar according to claim 1, wherein in S3, the pyrolyzed biochar is crushed into carbon powder with a mesh size of 100 - 200.
5. A method for capturing CO2 using high-temperature converter slag and biochar according to claim 1, wherein in S5, the bottom-blowing carbon dioxide gas pressure is controlled at 0.4 - 0.8 MPa.
6. A method for capturing CO2 using high-temperature converter slag and biochar according to claim 1, wherein in S5, the carbon powder injection amount is controlled at 10 - 50 kg / min.
7. A method for capturing CO2 using high-temperature converter slag and biochar according to claim 1, wherein in S5, two high-temperature steam inlets are symmetrically opened in the middle of the side wall of the high-temperature slag container.
8. A method for capturing CO2 using high-temperature converter slag and biochar according to claim 7, wherein in S5, the injection pressure of the steam is controlled at 0.2 - 0.4 MPa, and the steam flow rate is controlled at 40 - 60 L / min.
9. A method for capturing CO2 using high-temperature converter slag and biochar according to claim 1, wherein in S5, the temperature of the high-temperature steam is 200 - 600 °C.