Blast furnace carbon monoxide component field calculation method based on digital twinning

Abstract

The application provides a blast furnace carbon monoxide component field calculation method based on digital twinning, relates to the blast furnace carbon emission technical field, studies the distribution of the chemical components in the blast furnace, simulates the gas flow by adopting the Navier-Stokes equation, and solves the two-dimensional blast furnace fluid model by utilizing the grid-based finite difference algorithm, so as to obtain the gas velocity field, the temperature field and the solid temperature field. Meanwhile, the chemical kinetics model is established, the coke combustion, the carbon dissolution loss and the iron oxide reduction reaction are considered. The blast furnace is divided into five subspaces, and the corresponding reaction rate fields are calculated. Finally, the carbon monoxide concentration field is obtained through the iteration of the top gas data. The method can develop the carbon monoxide concentration field model meeting the industrial requirements in real time.

Description

Technical Field

[0001] This invention relates to the field of blast furnace carbon emission technology, and in particular to a method for calculating the carbon monoxide composition field of a blast furnace based on digital twins. Background Technology

[0002] As the core equipment in steel production, the blast furnace is a crucial reactor for reducing iron ore to molten iron. It consists of several parts: the hearth, the belly, and the furnace body. A gas purification system treats the gases emitted from the top of the blast furnace, removing impurities and recovering valuable gaseous components. Hot blast stoves provide high-temperature air to maintain the reducing atmosphere and thermal conditions within the blast furnace. The complex physical and chemical processes within the blast furnace, including high-temperature melting, gas flow, heat conduction, and chemical reactions, determine its operating efficiency and product quality. Oxygen and other gases are injected into the blast furnace through a spray system, where iron ore is reduced to molten iron, releasing a large amount of gaseous byproducts. Understanding the spatiotemporal distribution of various physical quantities within the blast furnace is crucial for optimizing its operation. Therefore, in-depth research on the field distribution within the blast furnace provides a key theoretical basis for process improvement, increased output, and reduced emissions.

[0003] In modern metallurgical engineering, the concept of fields is widely used in research, particularly in blast furnace smelting processes. Field analysis helps understand the spatial and temporal distribution of physical quantities, including temperature, pressure, flow rate, and composition. These physical quantities directly affect the reaction kinetics within the blast furnace and the quality of the final product. In the complex environment of a blast furnace, the interaction between temperature, flow, and composition fields is crucial. For example, the temperature field within a blast furnace can be simulated and evaluated using the inverse heat conduction method, and validated by combining a hierarchical modeling strategy with actual measurement data. This process helps understand the heat distribution within the blast furnace and provides key support for its stable operation. In the study of gas flow and composition fields in blast furnaces, computational fluid dynamics (CFD) techniques are widely used to simulate internal flow and temperature fields, particularly optimizing the flow and cooling effects around the injection nozzles. The main objective of this research is to improve the operating efficiency of the blast furnace and extend the service life of its components. The study of composition fields primarily focuses on the distribution of chemical composition within the blast furnace and its impact on the smelting process. The main components in a blast furnace, such as ore, coke, and auxiliary materials, undergo complex chemical reactions to produce molten iron and various byproducts. The efficiency and quality of these reactions are directly affected by the composition distribution. For example, optimizing the feedstock can reduce carbon dioxide emissions from the blast furnace, thereby improving environmental sustainability. Recent research has introduced the Harris Hawk Optimizer (HHO) and Grey Wolf Optimizer (GWO) to optimize blast furnace feedstock schemes to achieve energy conservation, emission reduction, and increased production. The composition of byproducts such as slag also warrants investigation. Techniques such as differential thermal analysis (DTA) and X-ray diffraction (XRD) can be used to comprehensively analyze the crystal structure of slag, revealing its role in the smelting process. The complexity of the compositional field in a blast furnace is reflected in the variability of its reactions; therefore, precise control of the composition is necessary to ensure the stability of the smelting process.

[0004] The study of gas composition fields has further deepened our understanding of blast furnace smelting. Major gases in the blast furnace, such as carbon monoxide (CO), play a crucial role in the reduction process. The distribution, flow characteristics, and composition of these gases directly affect the efficiency and stability of the reduction process.

[0005] For example, changes in oxygen concentration, temperature, and humidity within a blast furnace profoundly affect its gas distribution characteristics. These parameters can be optimized through numerical simulations to improve carbon monoxide utilization and reduce pressure losses. Modern processes are increasingly incorporating hydrogen-rich gases, such as natural gas, to reduce carbon emissions and improve energy efficiency. Furthermore, the presence of trace gases, such as chlorine, and their chemical reactions have attracted attention in research. The generation and chemical reactions of chlorine at high temperatures can have a corrosive effect on the long-term integrity of blast furnace equipment. These studies provide valuable insights into understanding gas flow, pressure changes, and their impact on blast furnace operation.

[0006] With the development of digital technology, digital twin technology has become an important tool for optimizing complex industrial processes. In the field of blast furnaces, digital twin technology provides a new solution for monitoring and predicting gas composition fields by synchronizing virtual models with the physical world. By integrating multiphysics, multiscale simulations, and sensor data, digital twin technology can simulate gas flow and composition changes inside the blast furnace in real time, especially the dynamic distribution of carbon dioxide. The core advantage of digital twins lies not only in their accurate mapping of the current state but also in their ability to predict future behavior. This characteristic provides key technical support for the intelligent and digital control of blast furnaces. Through the interaction of real-time and historical data, digital twin technology can accurately predict changes in carbon dioxide distribution and adjust production parameters accordingly, thereby optimizing blast furnace operating conditions, improving energy efficiency, and reducing emissions. This technology provides unprecedented accuracy and flexibility for modeling the carbon monoxide composition field in blast furnaces. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for calculating the carbon monoxide composition field in a blast furnace based on digital twins. This invention employs a systematic approach to study the complex chemical reactions occurring within the blast furnace, with particular focus on reaction rates related to gas-solid processes. By utilizing an unreacted contraction core model, we derived the reaction rate equations for key reactions, including primary combustion, carbon melting loss, and iron oxide reduction. These fundamental equations provide important insights into the dynamic interactions between reactants and their impact on operational efficiency.

[0008] A method for calculating the carbon monoxide composition field in a blast furnace based on digital twins includes the following steps:

[0009] Step 1: Describe the gas-solid reaction process using the unreacted core contraction model;

[0010] Specifically, assuming the solid reactants consist of tiny spherical particles, with gas surrounding these particles and promoting a chemical reaction that occurs only at the surfaces where the reactants meet, and the reaction interface gradually shrinks as the reaction proceeds; considering the effect of mass transfer resistance on the reaction rate, particularly the resistance encountered by the outer gas as it permeates the spherical shell and reacts with the unreacted core material, the relationship between the reaction rates is expressed as follows:

[0011]

[0012] Where x is the conversion rate, t is the reaction time, and A URCM is the reaction rate constant, E is energy, R is the gas constant, T is the reaction temperature, and exp() is the exponential operation of e.

[0013] Step 2: Calculate the chemical reaction for the complete combustion of carbon. The specific chemical equation is:

[0014] C + O₂ = CO₂ (2)

[0015] In the absence of sufficient oxygen, carbon undergoes incomplete combustion, as shown in the chemical equation:

[0016] 2C + O2 = 2CO (3)

[0017] The Arrhenius empirical formula establishes a mathematical relationship between reaction rate and ambient temperature. This equation describes the relationship between temperature and reaction rate as follows:

[0018]

[0019] In the formula, r represents the reaction rate, x and y represent reactants and products respectively, c represents the concentration of substances, a and b represent the reaction order, A is the frequency factor, Ea represents the activation energy of the reaction, R is the molar gas constant, and T represents the absolute temperature.

[0020] At high temperatures, carbon reacts with carbon dioxide to produce carbon monoxide; this reaction is represented by the following formula:

[0021] C + CO₂ = 2CO (5)

[0022] The reaction rate formula is:

[0023]

[0024] k1=exp(27.201-35900 / t) (7)

[0025] k2=exp(14.240-18350 / t) (8)

[0026] k3 = 10.3 (9)

[0027] k5=exp(29.588-36760 / t) (10)

[0028] E f =exp{(In(0.15))(t-1073) / 300} (11)

[0029] In the formula, m o c It is the initial carbon content of the coke. It is the number of coke particles per square meter, M c It is the molar mass of the gas, P T γ is the total pressure, γCO2, γCO, and γH2O represent the mole fractions of carbon dioxide, carbon monoxide, and water vapor, respectively, and t is the reaction time.

[0030] The reaction equation for the conversion of iron oxide (FeO) to ferrite at high temperature is as follows:

[0031] FeO + C = Fe + CO (12)

[0032] The reaction rate is expressed as:

[0033]

[0034]

[0035] Among them, T s For solid temperature, d represents the mole fraction of FeO. s It is the diameter of the solid particle, ψ s It is the solid form factor, ε s It refers to the porosity of the furnace charge.

[0036] The indirect reduction of iron oxide is described using the unreacted contractile core model, and the equation is as follows:

[0037] Fe₂O₃ + 3CO = 2Fe + 3CO₂ (17)

[0038] To quantify the entire process of reducing spherical iron oxide particles using reducing gas, three reaction process levels are considered: gas film diffusion (i.e., gas without contact with the ore); diffusion within the ore particles; and chemical reactions occurring at the reaction interface. By integrating these three processes of the indirect reduction reaction of iron oxide, the rate of the indirect reduction reaction is expressed as:

[0039]

[0040] k 11 =exp(5.8493-3460 / t) (19)

[0041] In the formula, K 11 It is the equilibrium constant of the reaction, Ds 11 This represents the gas diffusion efficiency, where φs is the solid shape factor. Number of solid particles per square meter, P CO Carbon monoxide reaction interface pressure, P CO e is the average carbon monoxide pressure, and fs is the iron ore reducing power.

[0042] Step 3: Generate the blast furnace modeling region. The mesh of the modeling region is generated using elliptic partial differential equations. Fluid flow in fluid dynamics is described by the Navier-Stokes equations (NS equations). The NS equations are simplified to a two-dimensional form, and the fluid in the blast furnace is considered incompressible. The two-dimensional NS equations are discretized and solved to derive the velocity and pressure fields inside the blast furnace. The temperatures measured by infrared thermocouples at temperature measurement points near the nozzle and furnace top are used as initial conditions. The temperature field of the blast furnace is obtained by bidirectional iterative solution using the discretized heat conduction differential equations. Specifically, the bidirectional iteration involves iterative calculations from the nozzle to the furnace top and from the furnace top to the nozzle, followed by weighted summation.

[0043] Step 4: Calculate the reaction rate. Assume that within a defined region, when multiple carbon chemical reactions occur simultaneously, the rate of carbon monoxide consumption is equal to the algebraic sum of the corresponding reaction rates.

[0044] For chemical reactions involving gases in a blast furnace, the reaction time of the gases involved in these reactions is calculated using the following formula:

[0045]

[0046] In the formula, treaction is the gas reaction time, and Vgas is the gas flow rate;

[0047] Step 5: Assuming that the chemical properties of the reactants are uniform in each subspace of the blast furnace, the gas composition at the injection port is used as the input and the gas composition at the top is used as the output. Construct a composition field model to predict the CO concentration at any given point in the blast furnace. The CO concentration at any location is the CO concentration at the injection port plus the CO concentration change along the gas path.

[0048] The CO concentration change is calculated using the reaction rate and gas residence time. The CO concentration measured at the top of the furnace provides the boundary conditions, and the CO concentration distribution from any point in the furnace to the top is derived from the overall reaction rate.

[0049] Step 6: Use a two-way calculation method for the composition field model to calculate the carbon monoxide concentration at the top of the furnace layer by layer from top to bottom, and then calculate the carbon monoxide concentration at the bottom of the furnace layer by layer from bottom to bottom; take the average of the results of the two calculations to obtain the final composition field model; use the composition field model to perform composition field calculations to obtain the current blast furnace operating status.

[0050] The beneficial effects of adopting the above technical solution are as follows:

[0051] This invention provides a method for calculating the carbon monoxide composition field inside a blast furnace based on digital twins, which can quickly calculate the carbon monoxide composition field inside the blast furnace. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the internal structure of the blast furnace of the present invention;

[0053] Figure 2 This is a schematic diagram of the carbon monoxide concentration field model established in the blast furnace of this invention;

[0054] Figure 3 This is the microstructure of the indirect reduction of iron oxide particles in this invention;

[0055] Figure 4 This is the iterative process of the temperature field in this invention;

[0056] Figure 5 This is a diagram illustrating the iterative process of the synthetic field in this invention;

[0057] Figure 6 This is a diagram of the calculation model for gas composition in the blast furnace of this invention;

[0058] Figure 7 This is a schematic diagram of the carbon monoxide concentration field of the present invention;

[0059] Figure 7 (a) - Carbon monoxide concentration field based on digital twin, Figure 7 (b) - Fluent-based carbon monoxide concentration field. Detailed Implementation

[0060] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0061] A method for calculating the carbon monoxide composition field in a blast furnace based on digital twins includes the following steps:

[0062] Step 1: Describe the gas-solid reaction process using the unreacted core contraction model;

[0063] Specifically, assuming the solid reactants consist of tiny spherical particles, with gas surrounding these particles and promoting a chemical reaction that occurs only at the surfaces where the reactants meet, and the reaction interface gradually shrinks as the reaction proceeds; considering the effect of mass transfer resistance on the reaction rate, particularly the resistance encountered by the outer gas as it permeates the spherical shell and reacts with the unreacted core material, the relationship between the reaction rates is expressed as follows:

[0064]

[0065] Where x is the conversion rate, t is the reaction time, and A URCM is the reaction rate constant, E is energy, R is the gas constant, T is the reaction temperature, and exp() is the exponential operation of e.

[0066] Taking the reduction of iron oxide as an example, in a reducing atmosphere, the outermost layer of iron oxide particles is initially completely reduced to elemental iron. Subsequently, the reducing gas permeates through the elemental iron and continues to react with the core of the iron oxide, generating intermediate products of the iron reduction process in the middle layer, particularly magnetite (Fe3O4) and iron oxide (Fe2O4). At the microscopic level, during the reduction process of iron oxide particles, the particles exhibit a multi-layered spherical structure.

[0067] Unlike precise simulations of microscopic chemical reactions, the unreacted core contraction model effectively simplifies complex reaction processes, thus enabling a more accurate description of chemical reaction rates associated with various gas-solid reaction models. Therefore, this model is used to analyze chemical reaction rates.

[0068] Step 2: Quantifying the rate of a chemical reaction, expressed as the change in the concentration of reactants or products per unit time. The magnitude of a chemical reaction rate is influenced by numerous factors, including the intrinsic properties and concentrations of the reactants, as well as external environmental conditions such as temperature and pressure. Calculating the chemical reaction rate is the initial step in quantifying chemical reactions within the blast furnace and is crucial for the subsequent development of the blast furnace composition field.

[0069] The complete combustion of carbon refers to the chemical reaction in which carbon (C) reacts fully with oxygen (O2) to produce carbon dioxide (CO2). The specific chemical equation is:

[0070] C + O₂ = CO₂ (2)

[0071] In the absence of sufficient oxygen, carbon undergoes incomplete combustion, leading to the formation of carbon monoxide (CO). The chemical equation is as follows:

[0072] 2C + O2 = 2CO (3)

[0073] The Arrhenius empirical formula establishes a mathematical relationship between reaction rate and ambient temperature. Here, the Arrhenius equation is given to describe the reaction rate of a combustion reaction. This equation describes the relationship between temperature and reaction rate as follows:

[0074]

[0075] In the formula, r represents the reaction rate, x and y represent reactants and products respectively, c represents the concentration of substances, a and b represent the reaction order, A is the frequency factor, Ea represents the activation energy of the reaction, R is the molar gas constant, and T represents the absolute temperature.

[0076] Carbon melting loss reaction can be classified as a carbon gasification reaction. At high temperatures, carbon reacts with carbon dioxide to produce carbon monoxide; during blast furnace smelting, the carbon melting loss reaction has a significant impact on the strength and energy consumption of coke. This reaction leads to thinning of the pore walls inside the coke, thereby reducing its strength and accelerating cracking. Furthermore, the carbon monoxide produced in this reaction is an important source of reducing agent in the blast furnace. This reaction is represented by the following formula:

[0077] C + CO₂ = 2CO (5)

[0078] The reaction rate formula for this reaction is:

[0079]

[0080] k1=exp(27.201-35900 / t) (7)

[0081] k2=exp(14.240-18350 / t) (8)

[0082] k3 = 10.3 (9)

[0083] k5=exp(29.588-36760 / t) (10)

[0084] E f =exp{(ln(0.15))(t-1073) / 300} (11)

[0085] In the formula, m o c It is the initial carbon content of the coke. It is the number of coke particles per square meter, M c It is the molar mass of the gas, P T γ is the total pressure, γCO2, γCO, and γH2O represent the mole fractions of carbon dioxide, carbon monoxide, and water vapor, respectively, and t is the reaction time.

[0086] The reduction of iron oxide is crucial in blast furnace ironmaking. Hematite is the most common form of iron ore. Iron oxide (FeO) transforms into ferrite at high temperatures. Ferrite is a non-stoichiometric iron oxide phase and is a melt. Notably, ferrite can undergo a direct reduction reaction with solid coke. This direct reduction reaction absorbs a large amount of heat, which is detrimental to the stability of the temperature field inside the blast furnace. Therefore, the occurrence of direct reduction reactions should be minimized. The reaction equation is:

[0087] FeO + C = Fe + CO (12)

[0088] Based on Hideki Miyasaka's treatment of this reaction, this study suggests that the direct reduction reaction occurs on the coke surface, where molten FeO is reduced to elemental iron. Larger coke particle sizes correspond to faster reaction rates, and the reaction rate is positively correlated with the activity of the molten phase. The reaction rate is expressed as:

[0089]

[0090] Among them, T s For solid temperature, d represents the mole fraction of FeO. s It is the diameter of the solid particle, ψ s It is the solid form factor, ε s It refers to the porosity of the furnace charge.

[0091] In blast furnaces, indirect reduction of iron oxide is the primary reduction mechanism. For example... Figure 3 As shown, in this process, carbon monoxide acts as a reducing agent, promoting the reduction of iron oxide to molten iron. This study uses the unreacted contraction core model to describe the indirect reduction of iron oxide, with the following equation:

[0092] Fe₂O₃ + 3CO = 2Fe + 3CO₂ (17)

[0093] According to the principle of the unreacted contracting core model, the reaction interface gradually moves inward and contracts towards the core of the iron ore particle. The outer layer of the iron ore reaction interface is composed of iron, the inner layer of ferrous oxide, and the reaction core is the unreacted ferric oxide. Carbon monoxide (CO) gas must diffuse to the reaction interface under the influence of various external forces to participate in the reduction reaction. Therefore, the contracting core model must consider the diffusion process of carbon monoxide gas into the interior of the spherical particle.

[0094] To quantify the entire process of reducing spherical iron oxide particles using reducing gas, three reaction process levels are considered: gas film diffusion (i.e., gas without contact with the ore); diffusion within the ore particles; and chemical reactions occurring at the reaction interface. By integrating these three processes of the indirect reduction reaction of iron oxide, the rate of the indirect reduction reaction is expressed as:

[0095]

[0096] k 11 =exp(5.8493-3460 / t) (19)

[0097] In the formula, K 11 It is the equilibrium constant of the reaction, Ds 11 This represents the gas diffusion efficiency, where φs is the solid shape factor. Number of solid particles per square meter, P CO Carbon monoxide reaction interface pressure, PCO e is the average carbon monoxide pressure, and fs is the iron ore reducing power.

[0098] In blast furnace operation, the carbon monoxide (CO) composition field is crucial for supporting on-site workers. By monitoring CO concentration in real time, this field helps identify potential operational problems early, significantly improving safety and efficiency. A comprehensive understanding of CO spatial distribution allows workers to optimize production operating parameters such as jet injection rate and coke charge, hot blast flow rate, etc., which are essential for maintaining the reducing atmosphere required for effective iron production.

[0099] Furthermore, the collection and analysis of CO data has deepened workers' understanding of the complex chemical reactions within the furnace. This knowledge enables them to make informed decisions and respond quickly to any anomalies that may arise. The integration of modern digital monitoring technologies further enhances this capability, allowing them to conduct real-time assessments to support safe and efficient operation.

[0100] Discussion: This study analyzed the chemical reactions occurring inside the blast furnace, specifically using the unreacted shrinking core model.

[0101] Table 1 Physical and Chemical Parameter Settings

[0102]

[0103] Table 2 Kinetic constants of carbon combustion reaction

[0104]

[0105]

[0106] Step 3: Generate the blast furnace modeling area, such as Figure 1 As shown, the experimental blast furnace in this embodiment is 27.1 meters high, with a maximum cross-sectional radius of 6.6 meters at its widest point. The mesh for the modeling region is generated using elliptic partial differential equations. Fluid flow in fluid dynamics is described by the Navier-Stokes equations (NS equations). The NS equations are simplified to a two-dimensional form, and the fluid in the blast furnace is considered incompressible. The two-dimensional NS equations are discretized and solved to derive the velocity and pressure fields inside the blast furnace. Temperatures measured by infrared thermocouples at temperature measurement points near the nozzle and furnace top are used as initial conditions. The temperature field of the blast furnace is obtained by bidirectional iterative solving of the discretized heat conduction differential equation between the nozzle and furnace top, as shown below. Figure 4 As shown, this method can accurately determine the overall temperature field of the blast furnace, which helps in calculating the carbon monoxide concentration field.

[0107] Step 4: To construct the composition field, it is necessary to analyze the gas composition in the blast furnace, such as... Figure 6As shown. The gases in a blast furnace mainly include nitrogen, oxygen, carbon monoxide, carbon dioxide, hydrogen, and various trace gases. It is worth noting that nitrogen does not participate in chemical reactions, while carbon monoxide and hydrogen primarily function as reducing gases to reduce iron oxide. Hydrogen accounts for a very small proportion of the blast furnace gases, typically not exceeding 3%. Carbon monoxide can be considered the most important reducing gas.

[0108] In the chemical reactions occurring in a blast furnace, if we take carbon monoxide as a representative, these reactions can be divided into two categories: reactions that consume carbon monoxide and reactions that produce carbon monoxide. To calculate reaction rates, it is assumed that within a defined region, when multiple carbon chemical reactions occur simultaneously, the rate of carbon monoxide consumption is equal to the algebraic sum of the corresponding reaction rates.

[0109] According to the definition of reaction rate, the net carbon monoxide consumption rate is determined by subtracting the carbon melting loss rate from the reaction rate of the indirect reduction reaction. It is important to note that a uniform carbon monoxide mass factor must be used when calculating reaction rates. In this embodiment, all reaction rates are standardized to (mol / L) s. -1 The product of reaction rate and reaction time gives the change in concentration, thus establishing a direct relationship between component concentration and reaction rate.

[0110] Changes in gas composition result in different distributions and physical properties in different regions.

[0111] The chemical reactions within the blast furnace are continuous, indicating that the reaction times of gases participating in the chemical reactions vary at different locations. The computational grid established for the blast furnace has a spacing of 100 mm. Therefore, for chemical reactions involving gases within the blast furnace, the reaction times of the gases participating in these reactions are calculated using the following formula:

[0112]

[0113] In the formula, treaction is the gas reaction time, and Vgas is the gas flow rate;

[0114] Step 5: Recognizing the inherent variations in the chemical properties of reactants at different locations within the blast furnace, a partitioned modeling strategy is employed. This method, based on empirical observations and operational data, divides the blast furnace into different regions, assuming uniform chemical properties of reactants within each subspace. This simplifies and accelerates reaction rate calculations, enabling localized analysis of physical and chemical behavior. This partitioning improves the accurate representation of spatial variations in reaction rates and composition, thereby deepening the understanding of the overall reaction dynamics. Considering the different chemical properties of reactants at different locations within the blast furnace, the furnace is divided into different regions, and the uniform chemical properties of reactants within each subspace are assumed.

[0115] Once the gas enters the blast furnace through the injection port, the chemical reaction continues. Nitrogen, due to its inertness, maintains a relatively stable concentration. In contrast, carbon monoxide (CO) is consumed in the reduction reaction and generated in other processes. Treating the blast furnace as a "black box," with the gas composition at the injection port as input and the gas composition at the top as output, a composition field model is constructed to predict the CO concentration at any given point within the blast furnace. The CO concentration at any location is the sum of the CO concentration at the injection port and the CO concentration variation along the gas path. This variation is determined by the CO consumption rate and the gas residence time. Using the top outlet as a reference point, a similar method is employed to infer the gas concentration throughout the blast furnace.

[0116] The CO concentration change is calculated using reaction rate and gas residence time. The CO concentration measured at the furnace top provides boundary conditions, combining empirical data with mechanism-based modeling to improve accuracy. The CO concentration distribution from any point in the furnace to the top can be derived from the overall reaction rate. This distribution, combined with the top gas boundary conditions, allows for precise determination of the gas composition concentration throughout the furnace.

[0117] The net carbon monoxide consumption rate was calculated and combined with the gas composition at the top of the blast furnace. Through bidirectional calculation, the final carbon monoxide composition field was obtained; for example... Figure 2 As shown, the changes in carbon monoxide concentration and its distribution exhibit the same trend as those based on precise mechanisms. Furthermore, while maintaining accuracy, the proposed method significantly improves computational speed, meeting the requirement for rapid construction of a carbon monoxide composition field. This makes it suitable for practical industrial applications and enables a more accurate depiction of carbon monoxide distribution within the furnace. The results demonstrate that the changes in carbon monoxide concentration and its spatial distribution are in excellent agreement with the trends predicted by more complex mechanism-based models, thus validating the effectiveness and reliability of our method.

[0118] Importantly, this method achieves high-precision results while significantly improving computational speed. This efficiency is crucial for meeting the practical needs of constructing carbon monoxide concentration fields in industrial applications. This capability is essential for the real-time monitoring and optimization of blast furnace operations, contributing to informed decision-making in dynamic production environments.

[0119] In this embodiment, to verify the effectiveness of the carbon monoxide concentration field modeling method, an iterative modeling process was performed based on blast furnace edge measurement data. The relevant physical and chemical parameters are listed in Tables 1 and 2, respectively. Some of these parameters were obtained from previous studies, while others were set according to the production process.

[0120] The chemical reactions in a blast furnace are primarily gas-solid phase reactions. From a microscopic reaction kinetics perspective, the gas-solid phase reaction process includes the following stages: First, gaseous reactants diffuse to the surface of solid reactants; then, they interact to form intermediate products; finally, the intermediate products further react to form the final products. Currently, the kinetic models used to describe gas-solid phase reactions mainly include volumetric models, stochastic porosity models, and unreacted core contraction models.

[0121] Step 6: To improve the accuracy of the model, a two-way calculation method was adopted for the component field model, such as... Figure 5 As shown, the carbon monoxide concentration at the top of the furnace is calculated layer by layer from top to bottom, and then the carbon monoxide concentration at the bottom of the furnace is calculated from bottom to bottom. The results of these two calculations are averaged to obtain the final composition field model. The composition field model is used to analyze the current operating status of the blast furnace to achieve efficient and safe production. The carbon monoxide concentration gradually decreases from bottom to top, and the concentration at the central axis is usually higher than that at the furnace wall. Compared with the accurate carbon monoxide composition field models obtained by using Fluent fluid dynamics software in other studies, the distribution of carbon monoxide concentration obviously shows a consistent trend. The composition field model obtained by Fluent software is very accurate; however, it requires a lot of computing power and time. The algorithm for calculating the carbon monoxide concentration field proposed in this embodiment only takes 0.374 seconds on a computer equipped with an Intel 13700KF CPU. Figure 7 As shown, according to Figure 7 (a) and Figure 7 (b) It can be seen that while maintaining a high level of accuracy, the proposed model significantly reduces the computation time, meeting the needs of the ironmaking industry for rapid digital twin models.

[0122] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in the embodiments of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in the embodiments of this disclosure.

Claims

1. A method for calculating the carbon monoxide composition field in a blast furnace based on digital twins, characterized in that, Includes the following steps: Step 1: Describe the gas-solid reaction process using the unreacted core contraction model; Step 2: Calculate the chemical reactions in the blast furnace; Step 3: Generate the blast furnace modeling region. The mesh of the modeling region is generated using elliptic partial differential equations. Fluid flow in fluid dynamics is described by the Navier-Stokes equations, i.e., the NS equations. The NS equations are simplified to a two-dimensional form, and the fluid in the blast furnace is considered incompressible. The two-dimensional Navier-Stokes equations were discretized and solved to derive the velocity and pressure fields inside the blast furnace; Step 4: Calculate the reaction rate. Assume that within a defined region, when multiple carbon chemical reactions occur simultaneously, the rate of carbon monoxide consumption is equal to the algebraic sum of the corresponding reaction rates. Step 5: Assuming that the chemical properties of the reactants are uniform in each subspace of the blast furnace, the gas composition at the injection port is used as the input and the gas composition at the top is used as the output. Construct a composition field model to predict the CO concentration at any given point in the blast furnace. The CO concentration at any location is the CO concentration at the injection port plus the CO concentration change along the gas path. Step 6: Use a two-way calculation method for the composition field model to calculate the carbon monoxide concentration at the top of the furnace layer by layer from top to bottom, and then calculate the carbon monoxide concentration at the bottom of the furnace layer by layer from bottom to top; take the average of the results of these two calculations to obtain the final composition field model; use the composition field model to perform composition field calculations to obtain the current blast furnace operating status; Step 1 specifically involves: assuming the solid reactants consist of tiny spherical particles, with gas surrounding these particles and promoting a chemical reaction, where the chemical reaction occurs only at the surfaces where the reactants contact each other, and the reaction interface gradually shrinks as the reaction proceeds; considering the effect of mass transfer resistance on the reaction rate, particularly the resistance encountered by the outer gas as it permeates the spherical shell and reacts with the unreacted core material, the relationship between the reaction rates is expressed as follows: Where x1 is the conversion rate, t is the reaction time, and A URCM R1 is the reaction rate constant, E is energy, R1 is the gas constant, T1 is the reaction temperature, and exp() is the exponential operation of e. Step 2 specifically involves: The specific chemical equation for the complete combustion of carbon is: C + O₂ = CO₂ (2) In the absence of sufficient oxygen, carbon undergoes incomplete combustion, as shown in the chemical equation: 2C + O2 = 2CO (3) The Arrhenius empirical formula establishes a mathematical relationship between reaction rate and ambient temperature, which is described as follows: In the formula, r represents the reaction rate, x and y represent reactants and products respectively, c represents the concentration of substances, a and b represent the reaction order, A is the frequency factor, Ea represents the activation energy of the reaction, R is the molar gas constant, and T represents the absolute temperature. At high temperatures, carbon reacts with carbon dioxide to produce carbon monoxide; this reaction is represented by the following formula: C + CO₂ = 2CO (5) The reaction rate formula is: k1=exp(27.201-35900 / t) (7) k2=exp(14.240-18350 / t) (8) k3＝10.3 (9) k5=exp(29.588-36760 / t) (10) E f =exp{(ln(0.15))(t-1073) / 300} (11) In the formula, m o c It is the initial carbon content of the coke. It is the number of coke particles per square meter, M c It is the molar mass of the gas, P T This is the total pressure; γCO2, γCO, and γH2O represent the mole fractions of carbon dioxide, carbon monoxide, and water vapor, respectively. The reaction equation for the conversion of iron oxide (FeO) to ferrite at high temperature is as follows: FeO + C = Fe + CO (12) The reaction rate is expressed as: Among them, T s For solid temperature, d represents the mole fraction of FeO. s It is the diameter of the solid particle, ψ s It is the solid form factor, ε s It refers to the porosity of the furnace charge; The indirect reduction of iron oxide is described using the unreacted contractile core model, as shown in the following equation: Fe₂O₃ + 3CO = 2Fe + 3CO₂ (17) To quantify the entire process of reducing spherical iron oxide particles using reducing gas, three reaction process levels are considered: gas film diffusion (i.e., gas without contact with the ore); diffusion within the ore particles; and chemical reactions occurring at the reaction interface. By integrating these three processes of the indirect reduction reaction of iron oxide, the rate of the indirect reduction reaction is expressed as: k 11 =exp(5.8493-3460 / t) (19) In the formula, K 11 It is the equilibrium constant of the reaction, Ds 11 This represents the gas diffusion efficiency, where φs is the solid shape factor. Number of solid particles per square meter, P CO Carbon monoxide reaction interface pressure, P CO e It is the mean pressure of carbon monoxide, f s It refers to the reducing power of iron ore.

2. The method for calculating the carbon monoxide composition field of a blast furnace based on digital twins according to claim 1, characterized in that, Step 3 specifically involves using the temperature measured by infrared thermocouples at temperature measurement points near the nozzle and furnace top as initial conditions, and then using a discretized heat conduction differential equation to perform a two-way iterative solution to obtain the temperature field of the blast furnace.

3. The method for calculating the carbon monoxide composition field of a blast furnace based on digital twins according to claim 2, characterized in that, The bidirectional iteration specifically involves performing iterative calculations from the nozzle to the furnace top and from the furnace top to the nozzle, and then performing a weighted summation.

4. The method for calculating the carbon monoxide composition field of a blast furnace based on digital twins according to claim 1, characterized in that, Step 4 specifically involves calculating the reaction time of gases involved in chemical reactions within the blast furnace using the following formula: In the formula t reaction It is the gas reaction time, V gas It is the gas flow velocity.

5. The method for calculating the carbon monoxide composition field of a blast furnace based on digital twins according to claim 1, characterized in that, The CO concentration change mentioned in step 5 is calculated using the reaction rate and gas residence time. The CO concentration measured at the top of the furnace provides the boundary conditions, and the CO concentration distribution from any point in the furnace to the top is derived from the overall reaction rate.

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