Preparation method for reducing carbon emission in deformed steel bar production process
By optimizing the rebar production process and energy recovery technology, the problem of high carbon emissions in the rebar production process has been solved, direct and indirect carbon emissions have been reduced, energy utilization efficiency has been improved, and domestic advanced level has been reached.
Patent Information
- Application Number
- CN202510600920.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-12
- Publication Date
- 2025-08-15
AI Technical Summary
The carbon emissions in the existing rebar production process are high, and there is a lack of effective emission reduction measures, especially in converter smelting, steelmaking and steel rolling processes, which makes it difficult to effectively control carbon emission management.
By optimizing the process flow of molten pretreatment, converter smelting, molten steel refining and steel rolling processes, combining energy recovery and by-product energy reforming technologies, including molten iron desulfurization, composite blowing, low-temperature rolling, high-efficiency heating furnaces, steam waste heat recovery and other measures, we will reduce direct and indirect carbon emissions.
It effectively reduces carbon emissions in the rebar production process, improves energy utilization efficiency, achieves the reduction of carbon emission targets, and reaches the domestic advanced level.
Smart Images
Figure CN120485455A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of threaded steel bar production, and in particular relates to a preparation method for reducing carbon emissions during threaded steel bar production. Background Art
[0002] Rebar bars produced at Baosteel's long product plants are important steel materials for basic building components and are widely used in the construction of buildings, bridges, roads, and other projects. Therefore, rebar accounts for a high proportion of carbon emissions among building materials, making carbon emission management in its manufacturing process particularly important. This patent analyzes the operation and transformation of carbon flows during the rebar production process to identify key areas for carbon reduction in rebar. Using the LCA method, the product's carbon emissions and carbon footprint data are quantified, and all potential influencing factors are calculated to identify key areas for carbon emission control, thereby achieving the goal of reducing carbon emissions during the rebar production process. This patent provides a preparation method for reducing carbon emissions during the rebar production process. Summary of the Invention
[0003] The purpose of the present invention is to provide a preparation method for reducing carbon emissions during the production process of threaded steel, thereby achieving the purpose of reducing carbon emissions during the production process of threaded steel.
[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:
[0005] The present invention provides a preparation method for reducing carbon emissions in the production process of rebar, which mainly reduces carbon emissions by optimizing raw materials, controlling processes, and recovering energy. Specific measures include the following aspects:
[0006] (1) Optimization of molten iron pretreatment (reducing converter smelting load)
[0007] Hot metal desulfurization pretreatment: Use KR mechanical stirring method or injection of magnesium-based desulfurizer to reduce the sulfur content of hot metal to ≤0.010%, reduce the consumption of slag-making agent (lime) during the converter smelting process, and reduce CO2 emissions generated by limestone decomposition.
[0008] Molten iron temperature control: The temperature of the molten iron entering the furnace is stabilized at 1250-1300℃, reducing the heating energy consumption during converter blowing.
[0009] (2) Optimization of converter smelting process (reducing direct carbon emissions)
[0010] Composite blowing technology: adopt top and bottom blown converter (BOF) and spray inert gas (such as Ar / N2) from the bottom to improve the stirring efficiency of molten steel, reduce the FeO content of final slag (≤15%), reduce iron loss and oxygen consumption, and thus reduce CO2 emissions.
[0011] Dynamic control model: Based on furnace gas analysis (real-time monitoring of CO / CO2), the oxygen supply intensity of the oxygen lance is adjusted to make the carbon-oxygen reaction more efficient and reduce the additional CO2 generation caused by overblowing.
[0012] End point carbon control: The end point carbon content is controlled at 0.10-0.15% to avoid post-blow decarbonization and reduce oxygen and lime consumption.
[0013] (3) Optimization of molten steel refining and continuous casting (reducing indirect carbon emissions)
[0014] High-efficiency LF refining: adopts low argon flow (≤5NL / min) and rapid heating process to shorten refining time and reduce power consumption.
[0015] Hot Charging and Hot Delivery (HCR): Billets with a temperature of ≥800℃ are directly fed into the rolling process to reduce reheating energy consumption.
[0016] (4) Energy saving in steel rolling process (reducing fuel consumption)
[0017] Low-temperature rolling technology: The final rolling temperature is controlled at 950-980℃ (the original process was 1000-1100℃) to reduce gas consumption.
[0018] High-efficiency heating furnace: Using thermal storage combustion technology (HTAC), the thermal efficiency is increased to ≥75% (traditional furnace is about 60%).
[0019] Furthermore, the slagging agent is lime.
[0020] Furthermore, it also includes: using OG method or LT dry method for dust removal, gas recovery volume ≥ 100Nm 3 / t steel, CO content ≥ 60%.
[0021] Furthermore, it also includes: through bag dust removal + desulfurization, the dust content of coal gas is ≤10mg / Nm 3 , sulfur content ≤50mg / Nm 3 .
[0022] Furthermore, it also includes: the purified coal gas is used for power generation or steel rolling heating furnace fuel, replacing part of the natural gas, and reducing CO2 emissions by ≥ 0.3t / t steel.
[0023] Furthermore, it also includes: steam waste heat recovery, converter vaporization cooling system: recovered steam pressure ≥1.0MPa, used for vacuum refining (VD) or plant heating, reducing the demand for purchased steam.
[0024] Furthermore, it also includes: by providing research on the operation and conversion of carbon flow in the rebar production process, identifying the carbon flow conversion process, calculating all potential influencing factors through LCA evaluation, quantifying the carbon emissions of the product, thereby identifying key areas for controlling carbon emissions, and formulating methods and measures to reduce carbon emissions in the rebar production process.
[0025] Furthermore, it specifically includes:
[0026] (1) Carbon flow analysis in rebar production
[0027] The chemical changes of carbon in the entire production process mainly occur in the coking, sintering, ironmaking and steelmaking processes. A table of the main transformation processes of carbon in steel production should be established;
[0028] (2) LCA evaluation study of rebar
[0029] The LCA evaluation research of rebar mainly includes the following aspects:
[0030] (2.1) Determine the functional unit and specify that the functional unit is 1 kg of rebar;
[0031] (2.2) Determine the research boundary and divide the rebar life cycle system boundary into three stages: the purchase of raw materials and energy extraction, product production stage; the recycling stage excluding the downstream use process;
[0032] (3) Life cycle inventory analysis
[0033] The LCA inventory data includes the input and output of carbon flows, and data types include upstream data, transportation data, and Baosteel production unit process input and output data. This data is ultimately summarized into eight categories: products, by-products, energy consumption, raw material consumption, auxiliary material consumption, atmospheric emissions, water emissions, and solid waste. The calculation data comes from on-site production data, and some data uses background database data. After data collection and organization, the inventory calculation is completed using the LCA calculation model.
[0034] (4) Life cycle impact assessment and result interpretation: analyze the environmental characteristics of rebar and select the life cycle impact assessment type suitable for Baosteel rebar;
[0035] (5) Critical path of carbon reduction process
[0036] During production, the direct resource and energy consumption and direct environmental emissions of each unit process accumulate throughout the process flow to the final product. Average sensitivity results indicate that process yield, or raw material utilization, is the most important factor influencing various environmental indicators. This sensitivity increases with each process step, indicating that later processes become increasingly important. Therefore, managing yield is crucial for reducing carbon footprints. Combining energy consumption analysis and life cycle assessment of rebar production, the following carbon reduction process pathways are proposed:
[0037] (5.1) The main factors affecting energy consumption are the consumption and calorific value of coke and coking coal, and the loss and emission of blast furnace gas;
[0038] (5.2) Improving the recovery rate of by-product gas is an important way to reduce energy consumption;
[0039] (5.3) The most important factor affecting water resource consumption is water loss during the water production process. Since coal-fired power generation consumes a lot of water, the electricity consumption of each process is also an important factor affecting water consumption indicators. It can be said that saving electricity is saving water.
[0040] (5.4) The amount of energy used and the structure of energy have equally important impacts on carbon emissions;
[0041] (5.5) Increasing the recycling of by-products such as blast furnace slag can effectively improve the carbon emissions of steel products throughout their life cycle;
[0042] (5.6) Based on the composition of HRB400E rebar, by adding alloying elements, high-strength steel bars and corrosion-resistant steel bars are produced, which can reduce the weight of construction steel by 20%-40% while meeting construction requirements, and at the same time extend the service life of the building.
[0043] Compared with the prior art, the present invention has the following beneficial technical effects:
[0044] By optimizing production processes to reduce direct carbon emissions during rolling production, and utilizing by-product energy reforming technology to improve energy efficiency and reduce indirect carbon emissions, we are effectively supporting the achievement of carbon emission reduction goals. BRIEF DESCRIPTION OF THE DRAWINGS
[0045] The present invention will be further described below with reference to the accompanying drawings.
[0046] Figure 1 The production process of rebar for Baosteel;
[0047] Figure 2 The distribution of coal and gas in major production processes;
[0048] Figure 3 It is the heat loss composition of rebar production process;
[0049] Figure 4 The LCA study boundary for rebar;
[0050] Figure 5 GWP100 life cycle phase distribution for HRB400E rebar. DETAILED DESCRIPTION
[0051] A preparation method for reducing carbon emissions in a rebar production process, comprising the following steps:
[0052] 1. Carbon flow analysis in rebar production
[0053] Throughout the production process ( Figure 1 ), the chemical transformation of carbon mainly occurs in the coking, sintering, ironmaking, steelmaking and other processes. The main transformation processes of carbon in steel production are shown in Table 1.
[0054] Table 1 Main conversion processes of carbon in production
[0055]
[0056]
[0057] After calculation, the distribution of coal and gas in the main production processes is as follows: Figure 1 As shown, the blast furnace ironmaking process accounts for 94.34%, and the ironmaking process is the focus of carbon flow conversion and control.
[0058] The carbon conversion process is accompanied by complex chemical reactions and physical changes. A large amount of heat is generated during the cooling of red coke and the production of coal gas and flue gas. The product temperatures of the main processes are shown in Table 2.
[0059] Table 2 Product temperature of main process
[0060]
[0061] As shown in Table 2, the operation and dissipation of the carbon flow generates sensible heat from coke, sintered ore, molten iron, molten steel, slag, billets, ingots, and flue gas, totaling approximately 450 kgce / t. This sensible heat is also lost during operation, primarily through heat dissipation from the furnace, cooling water, unrecovered flue gas, interface heat loss, and heat loss from the hot-rolled material.
[0062] The calculation formula for heat loss is:
[0063] Q=c×m×Δt
[0064] Where: Q is heat loss, kJ / t; c is the specific heat capacity of water, flue gas, molten iron, molten steel, ingots, and hot-rolled products, kJ / (m3·℃) or kJ / (t·℃); m is the mass of various waste heat carriers, t; Δt is the difference between the initial temperature and the reference temperature of various waste heat resources, °C. Calculations show that the heat loss in Baosteel's rebar production process is 107-142 kgce / t, accounting for approximately 17%-22% of purchased energy. The heat loss composition is as follows: Figure 2 shown.
[0065] The above data demonstrates that efficient carbon flow and effective recovery of waste heat and energy are crucial to energy efficiency and carbon emission reduction. Key research areas for carbon emission reduction should focus on reducing carbon inflow, improving energy efficiency, and effectively recovering waste heat and energy.
[0066] 2. LCA evaluation study of rebar
[0067] The LCA evaluation research of rebar mainly includes the following aspects.
[0068] (1) Determine the functional unit. The functional unit is 1 kg of rebar.
[0069] (2) Determine the research boundary. The boundary of the rebar life cycle system is divided into three stages: the purchase of raw materials and energy mining, product production stage; the recycling stage (excluding the downstream use process), such as Figure 3 shown.
[0070] (3) Life Cycle Inventory Analysis. The LCA inventory data includes the input and output of carbon flows (basic flows), and the data types include upstream stage data, transportation data, and Baosteel production unit process input and output data. These data are ultimately summarized into eight categories: products, by-products, energy consumption, raw material consumption, auxiliary material consumption, atmospheric emissions, water emissions, and solid waste. The calculation data comes from Baosteel's on-site production data, and some data uses background database data. After data collection and organization, the inventory calculation is completed using the LCA calculation model.
[0071] (4) Life cycle impact assessment and result interpretation. The environmental characteristics of rebar were analyzed and the life cycle impact assessment type suitable for Baosteel rebar was selected. The specific results are shown in Table 3. Figure 4 .
[0072] Table 3 Life cycle impact assessment results of 1kg HRB400E rebar
[0073]
[0074] From Table 3, Figure 4The analysis results show that internal CO2 emissions account for 81.67% of the total emissions, the main sources of which are the combustion of fuel and the decomposition of ores such as limestone and dolomite. External transportation accounts for 3.62%, mainly the transportation of materials. Upstream loads account for 24.96%, and the income from external use of by-products accounts for 10.25%.
[0075] 3. Critical Path of Carbon Reduction Process
[0076] During production, the direct resource and energy consumption and direct environmental emissions of each unit process accumulate throughout the process flow to the final product. Average sensitivity results indicate that process yield (or raw material utilization) is the most important factor influencing various environmental indicators. The average sensitivity increases with each process step, indicating that the importance of subsequent processes increases. Therefore, managing yield is crucial for reducing carbon footprints. Combining energy consumption analysis and life cycle assessment of rebar production, the following carbon reduction process pathway is proposed.
[0077] (1) The main factors affecting energy consumption are the consumption and calorific value of coke and coking coal, the loss and emission of blast furnace gas, etc.
[0078] (2) Improving the recovery rate of by-product gas is an important way to reduce energy consumption;
[0079] (3) The important factor affecting water resource consumption is the water loss in the water production process. Since the water consumption in the coal-fired power generation process is relatively high, the power consumption of each process is also an important factor affecting the water consumption index. It can be said that saving electricity is saving water.
[0080] (4) The amount of energy used and the structure of energy (such as energy types and clean energy use) are equally important in affecting carbon emissions;
[0081] (5) Increasing the recycling of by-products such as blast furnace slag can effectively improve the carbon emissions of steel products throughout their life cycle.
[0082] (6) By adding alloying elements to the composition of HRB400E rebar, high-strength and corrosion-resistant rebars such as HRB500E and HRB600 can be produced. This reduces the weight of construction steel by 20% to 40% while still meeting building requirements. This also extends the service life of buildings. Therefore, from a full life cycle perspective, vigorously promoting the application of high-performance rebar products is an important means of emission reduction and is of great significance to reducing carbon emissions in downstream industries.
[0083] By implementing a series of energy-saving and carbon-reduction measures, Baosteel published an Environmental Product Declaration for its hot-rolled ribbed steel bars on the steel industry's EPD platform in December 2022. Baosteel's rebar carbon emissions have reached advanced domestic standards. By optimizing production processes to reduce direct carbon emissions from the rolling process and utilizing by-product energy reforming technology to improve energy efficiency and reduce indirect carbon emissions, Baosteel is effectively supporting the achievement of its carbon emission reduction goals.
[0084] Optimized specific production process and parameter control:
[0085]
[0086] Technical solutions for by-product energy reforming:
[0087] (1) Recovery and utilization of converter gas (LDG)
[0088] High efficiency recovery: OG method or LT dry method dust removal is adopted, gas recovery volume ≥100Nm 3 / t steel, CO content ≥ 60%.
[0089] Gas purification: through bag dust removal + desulfurization, the dust content of gas is ≤10mg / Nm 3 , sulfur content ≤50mg / Nm 3 .
[0090] Energy utilization: The purified coal gas is used for power generation (CCPP) or as fuel for steel rolling heating furnaces, replacing part of the natural gas and reducing CO2 emissions by ≥0.3t / t of steel.
[0091] (2) Steam waste heat recovery
[0092] Converter vaporization cooling system: Recovered steam pressure ≥1.0MPa, used for vacuum refining (VD) or plant heating, reducing the demand for purchased steam.
[0093] Specific examples:
[0094] Process parameters after process optimization:
[0095] Molten iron [S] = 0.008%, converter end point [C] = 0.12%, hot charging temperature 820℃.
[0096] The final rolling temperature of steel is 950℃ and the heating furnace efficiency is 78%.
[0097] Converter gas recovery capacity 110Nm 3 / t steel, used for power generation.
[0098] Carbon emission result: 2.20tCO2 / t rebar (covering direct and indirect emissions).
[0099] Optimize process parameters before processing:
[0100] Molten iron [S] = 0.025%, converter end point [C] = 0.05% (overblowing), cold-charged continuous casting billet.
[0101] The final rolling temperature is 1000℃ and the heating furnace efficiency is 60%.
[0102] The converter gas is not recovered and is released directly.
[0103] Carbon emission result: 2.40tCO2 / t rebar.
[0104] By optimizing processes and using by-product energy reforming technology, carbon emissions have been reduced by 9%. Furthermore, it is one of the first production lines in the domestic steel industry to be certified by the EPD platform, demonstrating its excellence in reducing carbon emissions during rebar production.
[0105] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.
Claims
1. A preparation method for reducing carbon emissions in the production process of threaded steel, characterized in that: Carbon emissions are mainly reduced through raw material optimization, process control, and energy recovery. Specific measures include the following: (1) Optimization of molten iron pretreatment Hot metal desulfurization pretreatment: Use the KR mechanical stirring method or inject magnesium-based desulfurizer to reduce the sulfur content of hot metal to ≤0.010%, reduce the consumption of slagging agents during the converter smelting process, and reduce CO2 emissions from limestone decomposition; Molten iron temperature control: The temperature of the molten iron entering the furnace is stabilized at 1250-1300℃, reducing the energy consumption of heating during converter blowing; (2) Optimization of converter smelting process Composite blowing technology: adopts top-bottom combined blowing converter, and injects inert gas from the bottom to improve the stirring efficiency of molten steel, reduce the FeO content of the final slag to ≤15%, reduce iron loss and oxygen consumption, and thus reduce CO2 emissions; Dynamic control model: Based on furnace gas analysis, the oxygen supply intensity of the oxygen lance is adjusted to make the carbon-oxygen reaction more efficient and reduce the additional CO2 generation caused by overblowing; End point carbon control: The end point carbon content is controlled at 0.10-0.15% to avoid post-blow decarbonization and reduce oxygen and lime consumption; (3) Molten steel refining and continuous casting optimization High-efficiency LF refining: adopting low argon flow ≤5NL / min and rapid temperature rise process to shorten refining time and reduce power consumption; Hot charging and hot delivery of continuous casting billets: billets with a temperature of ≥800℃ can be directly delivered to the steel rolling process, reducing reheating energy consumption; (4) Energy saving in steel rolling process Low temperature rolling technology: the final rolling temperature is controlled at 950-980℃ to reduce gas consumption; High-efficiency heating furnace: adopts heat storage combustion technology, and the thermal efficiency is increased to ≥75%.
2. The method for reducing carbon emissions in the production process of threaded steel according to claim 1, characterized in that: The slagging agent is lime.
3. The method for reducing carbon emissions in the production process of threaded steel according to claim 1, characterized in that: Also includes: Use OG method or LT dry method for dust removal, gas recovery volume ≥ 100Nm³ / t steel, CO content ≥ 60%.
4. The method for reducing carbon emissions in the production process of threaded steel according to claim 1, characterized in that: Also includes: Through bag dust removal + desulfurization, the dust content of coal gas is ≤10mg / Nm³ and the sulfur content is ≤50mg / Nm³.
5. The method for reducing carbon emissions in the production process of threaded steel according to claim 1, characterized in that: Also includes: The purified coal gas is used for power generation or as fuel for steel rolling heating furnaces, replacing part of the natural gas and reducing CO2 emissions by ≥0.3t / t of steel.
6. The method for reducing carbon emissions in the production process of threaded steel according to claim 1, characterized in that: Also includes: Steam waste heat recovery, converter vaporization cooling system: recovered steam pressure ≥1.0MPa, used for vacuum refining (VD) or plant heating, reducing the demand for purchased steam.
7. The method for reducing carbon emissions in the production process of threaded steel according to claim 1, characterized in that: Also includes: By providing research on the operation and conversion of carbon flow in the rebar production process, identifying the carbon flow conversion process, and through LCA evaluation, calculating all potential influencing factors, and quantifying the carbon emissions of the product, we can identify key areas for controlling carbon emissions and develop methods and measures to reduce carbon emissions in the rebar production process.
8. The method for reducing carbon emissions in the production process of threaded steel according to claim 7, characterized in that: Specifically include: (1) Carbon flow analysis in rebar production The chemical changes of carbon in the entire production process mainly occur in the coking, sintering, ironmaking and steelmaking processes. A table of the main transformation processes of carbon in steel production should be established; (2) LCA evaluation study of rebar The LCA evaluation research of rebar mainly includes the following aspects: (2.1) Determine the functional unit and specify that the functional unit is 1 kg of rebar; (2.2) Determine the research boundary and divide the rebar life cycle system boundary into three stages: purchasing raw materials and energy extraction, and product production; The recycling stage does not include downstream use; (3) Life cycle inventory analysis. The LCA inventory data includes the input and output of carbon flows, and the data types include upstream stage data, transportation data, and Baosteel production unit process input and output data. These data are ultimately summarized into eight categories: products, by-products, energy consumption, raw material consumption, auxiliary material consumption, atmospheric emissions, water emissions, and solid waste. The calculation data comes from on-site production data, and some data uses background database data. After the data is collected and organized, the inventory calculation is completed using the LCA calculation model. (4) Life cycle impact assessment and result interpretation: analyze the environmental characteristics of rebar and select the life cycle impact assessment type suitable for Baosteel rebar; (5) Key paths of carbon reduction processes During production, the direct resource and energy consumption and direct environmental emissions of each unit process accumulate throughout the process flow to the final product. Average sensitivity results indicate that process yield, or raw material utilization, is the most important factor influencing various environmental indicators. This sensitivity increases with each process step, indicating that later processes become increasingly important. Therefore, managing yield is crucial for reducing carbon footprints. Combining energy consumption analysis and life cycle assessment of rebar production, the following carbon reduction process pathways are proposed: (5.1) The main factors affecting energy consumption are the consumption and calorific value of coke and coking coal, and the loss and emission of blast furnace gas; (5.2) Improving the recovery rate of by-product gas is an important way to reduce energy consumption; (5.3) The main factor affecting water resource consumption is water loss during the water production process. Since coal-fired power generation consumes a lot of water, the electricity consumption of each process is also a major factor affecting water consumption indicators. It can be said that saving electricity is also saving water. (5.4) Energy consumption and energy structure have equally important impacts on carbon emissions; (5.5) Increasing the recycling of by-products such as blast furnace slag can effectively improve the carbon emissions of steel products throughout their life cycle; (5.6) Based on the composition of HRB400E rebar, high-strength steel bars and corrosion-resistant steel bars are produced by adding alloying elements. This reduces the weight of construction steel by 20%-40% while still meeting construction requirements. This also extends the service life of the building.