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

Abstract

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

Description

Technical Field

[0001] The present invention relates to the technical field of blast furnace carbon emission, and in particular to a method for calculating a blast furnace carbon monoxide composition field based on digital twin. Background Art

[0002] As the core equipment of steel production, the blast furnace is the key reactor for reducing iron ore to molten iron. It consists of several parts: the hearth, the belly and the furnace body. The gas purification system processes the gas discharged from the top of the blast furnace, removes impurities and recovers valuable gas components. The hot blast stove provides high-temperature air to maintain the reducing atmosphere and thermal conditions in the blast furnace. The complex physical and chemical processes in the blast furnace, including high-temperature smelting, 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 the injection system, where iron ore is reduced to molten iron and a large amount of gaseous by-products are released. Understanding the spatiotemporal distribution of various physical quantities in the blast furnace is crucial to optimizing its operation. Therefore, in-depth research on the field distribution in the blast furnace provides a key theoretical basis for process improvement, increased output and reduced emissions.

[0003] In modern metallurgical engineering, the field concept has been widely used in research, especially in the blast furnace smelting process. Field analysis helps to understand the distribution of physical quantities in space and time, including temperature, pressure, flow rate and composition. These physical quantities directly affect the reaction dynamics in the blast furnace and the quality of the final product. In a complex environment such as a blast furnace, the interaction between the temperature field, flow field and composition field is crucial. For example, the temperature field in the blast furnace can be simulated and evaluated by the inverse heat conduction method, and verified by combining the hierarchical modeling strategy with actual measurement data. This process helps to understand the heat distribution in the blast furnace and provides key support for the stable operation of the blast furnace. In the study of the airflow and composition field of the blast furnace, computational fluid dynamics (CFD) technology is widely used to simulate the internal flow and temperature field, especially to optimize the flow and cooling effect around the injection nozzle. The main purpose of this study is to improve the operating efficiency of the blast furnace and extend the service life of its components. The study of the composition field mainly focuses on the distribution of chemical composition inside the blast furnace and its influence 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 by-products, and the efficiency and quality of these reactions are directly affected by the composition distribution. For example, by optimizing the batching, CO2 emissions from blast furnaces can be reduced, thereby improving environmental sustainability. Recent studies have introduced the Harris Eagle Optimizer (HHO) and the Gray Wolf Optimizer (GWO) to optimize blast furnace batching schemes to achieve the goals of energy saving, emission reduction, and increased production. The composition of by-products such as slag is also worthy of study. Through technical methods such as differential thermal analysis (DTA) and X-ray diffraction (XRD), the crystal structure of slag can be fully analyzed to reveal its role in the smelting process. The complexity of the composition field in the blast furnace is reflected in the variability of its reactions, so precise control of the composition is required to ensure the stability of the smelting process.

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

[0005] For example, changes in oxygen concentration, temperature, and humidity in a blast furnace can profoundly affect the gas distribution characteristics within the blast furnace. These parameters can be optimized through numerical simulation to improve carbon monoxide utilization and reduce pressure losses. Modern processes gradually introduce hydrogen-rich gases, such as natural gas, to reduce carbon emissions and improve energy efficiency. In addition, 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 ironmaking 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 multi-physics fields, multi-scale simulations, and sensor data, digital twin technology can simulate the gas flow and composition changes inside the blast furnace in real time, especially the dynamic distribution of the carbon dioxide composition field. The core advantage of digital twins lies not only in its accurate mapping of the current state, but also in its ability to predict future behavior. This feature 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] In view of the shortcomings of the prior art, the present invention provides a method for calculating the carbon monoxide composition field in a blast furnace based on digital twins; the present invention adopts a systematic approach to study the complex chemical reactions occurring in the blast furnace, with particular attention to the reaction rates associated with the gas-solid process. By utilizing the unreacted shrinking core model, we derive reaction rate equations for key reactions, including primary combustion, carbon melting loss, and iron oxide reduction reactions. These fundamental equations provide important insights into the dynamic interactions between reactants and their impact on operating efficiency.

[0008] A method for calculating carbon monoxide composition field of a blast furnace based on digital twin, comprising the following steps:

[0009] Step 1: Use the unreacted core shrinkage model to describe the gas-solid reaction process;

[0010] Specifically, it is assumed that the solid reactants are composed of tiny spherical particles, and the gas surrounds these particles and promotes the chemical reaction, in which the chemical reaction only occurs on the surface where the reactants are in contact. As the reaction proceeds, the reaction interface gradually shrinks; considering the effect of mass transfer resistance on the reaction rate, especially the resistance encountered by the outer gas when penetrating the spherical shell to react with the unreacted core material, the relationship between the obtained reaction rates is expressed as:

[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.

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

[0014] C+O2=CO2 (2)

[0015] In the absence of sufficient oxygen, carbon will undergo incomplete combustion, and the chemical equation is:

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

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

[0018]

[0019] Where r represents the reaction rate, x and y represent the reactants and products respectively, c represents the concentration of the substance, 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 form carbon monoxide; the reaction is represented by the following equation:

[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 is the initial carbon content of the coke, is the number of coke particles per square meter, M c is the molar mass of the gas, P T is the total pressure, γCO2, γCO, 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 into ferrite at high temperature is:

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

[0032] The reaction rate is expressed as:

[0033]

[0034]

[0035] Among them, T s is the solid temperature, is the mole fraction of FeO, d s is the solid particle diameter, ψ s is the solid shape factor, ε s is the porosity of the charge.

[0036] The unreacted shrinking core model is used to describe the indirect reduction of iron oxide, and the equation is as follows:

[0037] Fe2O3+3CO=2Fe+3CO2 (17)

[0038] In order to quantify the whole process of reducing spherical iron oxide particles using reducing gas, three reaction process levels are considered: gas film diffusion, that is, the gas does not contact the ore; diffusion inside the ore particles; and chemical reactions occurring at the reaction interface. By integrating the 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 is the equilibrium constant of the reaction, Ds 11 represents the gas diffusion efficiency, 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, fs is the degree of reduction of iron ore;

[0042] Step 3: Generate a blast furnace modeling area. The mesh of the modeling area is generated using elliptic partial differential equations. The Navier-Stokes equations, i.e., NS equations, are used to describe the fluid flow in fluid mechanics. The NS equations are simplified to a two-dimensional form, and the fluid in the blast furnace is regarded as incompressible. The two-dimensional NS equations are discretized and solved to derive the velocity field and pressure field inside the blast furnace. The temperature measured by infrared thermocouples at the temperature measurement points near the nozzle and the furnace top is used as the initial condition, and the discretized heat conduction differential equations are used to perform bidirectional iterative solutions to obtain the temperature field of the blast furnace. The bidirectional iteration is specifically as follows: iterative calculations are performed from the nozzle to the furnace top and from the furnace top to the nozzle, and then weighted summation is performed.

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

[0044] For chemical reactions involving gases in the blast furnace, the reaction times of the gases participating in these reactions are calculated using the following formula:

[0045]

[0046] Where treat is the gas reaction time, Vgas is the gas flow rate;

[0047] Step 5: Assuming that the chemical properties of the reactants in each subspace of the blast furnace are uniform, the gas composition at the injection port is taken as input and the gas composition at the top is taken as output. A composition field model is constructed 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 variation along the gas path;

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

[0049] Step 6: A bidirectional calculation method is used for the composition field model to calculate the carbon monoxide concentration at the furnace top layer by layer from top to bottom, and then calculate the carbon monoxide concentration at the furnace bottom from bottom to bottom; the results of these two calculations are averaged to obtain the final composition field model; the composition field calculation is performed through the composition field model to obtain the current blast furnace operation status.

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

[0051] The present invention provides a method for calculating the carbon monoxide composition field of a blast furnace based on digital twin, which can quickly calculate the carbon monoxide composition field inside the blast furnace. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0054] Figure 3 The microstructure of the indirectly reduced iron oxide particles of the present invention;

[0055] Figure 4 It is the iterative process of the temperature field of the present invention;

[0056] Figure 5 It is a diagram of the iterative process of synthesizing the field of the present invention;

[0057] Figure 6 The gas composition calculation model diagram in the blast furnace of the present 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)-Carbon monoxide concentration field based on Fluent. DETAILED DESCRIPTION

[0060] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0061] A method for calculating carbon monoxide composition field of a blast furnace based on digital twin, comprising the following steps:

[0062] Step 1: Use the unreacted core shrinkage model to describe the gas-solid reaction process;

[0063] Specifically, it is assumed that the solid reactants are composed of tiny spherical particles, and the gas surrounds these particles and promotes the chemical reaction, in which the chemical reaction only occurs on the surface where the reactants are in contact. As the reaction proceeds, the reaction interface gradually shrinks; considering the effect of mass transfer resistance on the reaction rate, especially the resistance encountered by the outer gas when penetrating the spherical shell to react with the unreacted core material, the relationship between the obtained reaction rates is expressed as:

[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.

[0066] Taking the reduction of iron oxide as an example, in a reducing atmosphere, the outermost layer of the iron oxide particle is initially completely reduced to elemental iron. Subsequently, the reducing gas permeates through the elemental iron and continues to react with the inner core of the iron oxide, generating intermediate products of the iron reduction process in the middle layer, especially ferroferric oxide and magnetite. At the microscopic level, during the reduction process of the iron oxide particle, the particle exhibits a multi-layer spherical structure.

[0067] Unlike the accurate simulation of microscopic chemical reactions, the unreacted core shrinkage model effectively simplifies the complex reaction process, thereby being able to more accurately describe the chemical reaction rates associated with various gas-solid reaction models. Therefore, this model is used to analyze the chemical reaction rates.

[0068] Step 2: Chemical Reaction Rate quantifies the speed of a chemical reaction, expressed as the change in concentration of reactants or products per unit time. The magnitude of a chemical reaction rate is affected by many 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 a blast furnace and is critical to the subsequent development of the blast furnace composition field.

[0069] Calculating the complete combustion chemical reaction of carbon refers to the process in which carbon C fully reacts 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 will undergo incomplete combustion, resulting in the formation of carbon monoxide CO. The chemical equation is:

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

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

[0074]

[0075] Where r represents the reaction rate, x and y represent the reactants and products respectively, c represents the concentration of the substance, 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] The carbon loss by melting reaction can be classified as a carbon gasification reaction. At high temperatures, carbon reacts with carbon dioxide to form carbon monoxide; during blast furnace smelting, the carbon loss by melting reaction has a significant impact on the strength and energy consumption of coke. This reaction causes the pore walls inside the coke to become thinner, thereby reducing its strength and accelerating its cracking. In addition, the carbon monoxide produced by this reaction is an important source of reducing agent in the blast furnace. The reaction is expressed 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 is the initial carbon content of the coke, is the number of coke particles per square meter, M c is the molar mass of the gas, P T is the total pressure, γCO2, γCO, γH2O represent the mole fractions of carbon dioxide, carbon monoxide and water vapor respectively, and t is the reaction time.

[0086] In the blast furnace ironmaking process, the reduction of iron oxide is the key. Among iron ores, hematite is the most common form of iron ore. Iron oxide FeO will be converted into ferrite at high temperature. Ferrite is a non-stoichiometric iron oxide phase and a melt. It is worth noting that ferrite can undergo a direct reduction reaction with coke solids. The direct reduction reaction will absorb a lot of heat, which is not conducive to the stability of the temperature field inside the blast furnace. The occurrence of direct reduction reaction 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 proposes that the direct reduction reaction occurs on the coke surface, where the molten FeO is reduced to elemental iron. It is observed that larger coke particle sizes correspond to faster reaction rates, which are positively correlated with the activity of the molten phase; the reaction rate is expressed as:

[0089]

[0090] Among them, T s is the solid temperature, is the mole fraction of FeO, d s is the solid particle diameter, ψ s is the solid shape factor, ε s is the porosity of the charge.

[0091] In the blast furnace, indirect reduction of iron oxide is the main reduction mechanism. Figure 3 As shown, in this process, carbon monoxide acts as a reducing agent to promote the reduction of iron oxide to molten iron. This study uses the unreacted shrinking core model to describe the indirect reduction of iron oxide, and the equation is as follows:

[0092] Fe2O3+3CO=2Fe+3CO2 (17)

[0093] According to the principle of the unreacted shrinking core model, the reaction interface gradually moves inward and shrinks toward the core of the iron ore particle. The outer layer of the iron ore reaction interface is composed of iron, the inner layer is composed of ferrous oxide, and the reaction core is the iron oxide that has not yet participated in the reaction. Carbon monoxide (CO) gas must diffuse to the reaction interface under the action of various external forces to participate in the reduction reaction. Therefore, the shrinking core model must consider the diffusion process of carbon monoxide gas into the interior of the spherical particle.

[0094] In order to quantify the whole process of reducing spherical iron oxide particles using reducing gas, three reaction process levels are considered: gas film diffusion, that is, the gas does not contact the ore; diffusion inside the ore particles; and chemical reactions occurring at the reaction interface. By integrating the 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 is the equilibrium constant of the reaction, Ds 11 represents the gas diffusion efficiency, 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, fs is the degree of reduction of iron ore;

[0098] In the operation of a blast furnace, the CO composition field is essential for the support of workers on site. By monitoring CO concentrations in real time, the field helps to detect potential operating problems at an early stage, thereby significantly improving safety and efficiency. A comprehensive understanding of the spatial distribution of CO allows workers to optimize production operating parameters such as injection rate and coke addition, hot air flow, etc., which are essential to maintain the reducing atmosphere required for effective iron production.

[0099] Additionally, the collection and analysis of CO data deepens workers’ understanding of the complex chemical reactions within the furnace. This knowledge enables them to make informed decisions and respond quickly to abnormal situations that may arise. The integration of modern digital monitoring technology further enhances this capability, allowing them to conduct real-time assessments to support safe and efficient operations.

[0100] Discussion This study analyzed the chemical reactions occurring in a 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 and has a maximum cross-sectional radius of 6.6 meters at its widest point. The mesh of the modeling area is generated using elliptic partial differential equations. The Navier-Stokes equations, or NS equations, describe the fluid flow in fluid mechanics. 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 field and pressure field inside the blast furnace. The temperature measured by infrared thermocouples is used as the initial condition at the temperature measurement points near the nozzle and the furnace top. The discretized heat conduction differential equations are used to perform bidirectional iterative solutions between the nozzle and the furnace top to obtain the temperature field of the blast furnace, as shown in FIG. Figure 4 As shown; this method can obtain the overall temperature field of the blast furnace with high accuracy, which is helpful for calculating the carbon monoxide concentration field.

[0107] Step 4: In order 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 the 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 the chemical reaction, and carbon monoxide and hydrogen are mainly used as reducing gases to reduce iron oxide. Hydrogen accounts for a very small proportion of blast furnace gas, usually not more than 3%. Carbon monoxide can be regarded as the most important reducing gas.

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

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

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

[0111] The chemical reactions in the blast furnace are continuous, which means that the reaction time of the gases participating in the chemical reactions is different at different locations. The spacing of the computational grid established for the blast furnace is 100 mm. Therefore, for the chemical reactions involving gases in the blast furnace, the reaction time of the gases participating in these reactions is calculated using the following formula:

[0112]

[0113] Where treat is the gas reaction time, Vgas is the gas flow rate;

[0114] Step 5: Recognizing the inherent variation in the chemical properties of reactants at different locations within the blast furnace, a partitioning modeling strategy is adopted. This approach divides the blast furnace into different regions based on empirical observations and operational data, assuming that the chemical properties of the reactants in each subspace of the blast furnace are uniform, simplifying and improving the reaction rate calculation speed, thereby enabling local analysis of physical and chemical behaviors. This partitioning improves the accurate representation of the spatial variation of reaction rates and components, thereby deepening the understanding of the overall reaction dynamics. Considering the different chemical properties of reactants at different locations in the blast furnace, the blast furnace is divided into different regions, and the chemical properties of the reactants in each subspace are assumed to be uniform;

[0115] Once the gas enters the blast furnace through the injection port, chemical reactions continue. Nitrogen remains relatively stable in concentration due to its inertness. In contrast, carbon monoxide (CO) is consumed in the reduction reaction and produced in other processes. The blast furnace is considered 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 in the blast furnace. The CO concentration at any location is the CO concentration at the injection port plus 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 approach is used to infer the gas concentration throughout the blast furnace.

[0116] The CO concentration change is calculated from the reaction rate and gas residence time, and the CO concentration measured at the furnace top provides the boundary condition, 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 condition, can accurately determine the gas component concentration throughout the furnace.

[0117] The net consumption rate of carbon monoxide is calculated and combined with the gas composition at the top of the blast furnace. Through two-way calculation, the final carbon monoxide composition field is obtained; Figure 2 As shown, the changes in carbon monoxide concentration and its distribution show the same trend compared to the model based on the exact mechanism. In addition, while maintaining accuracy, the proposed method significantly improves the calculation speed, meets the requirements of rapidity required to construct the carbon monoxide composition field, is suitable for practical industrial applications, and can more accurately depict the distribution of carbon monoxide in the furnace. The results show that the changes in carbon monoxide concentration and its spatial distribution are very consistent with the trends predicted by the more complex mechanism-based model, thus verifying the effectiveness and reliability of our method.

[0118] Importantly, the method achieves high accuracy results while significantly increasing computational speed. This efficiency is critical to meeting the practical needs of constructing carbon monoxide concentration fields for industrial applications. This capability is essential for real-time monitoring and optimization of blast furnace operations, helping to make informed decisions in dynamic production environments.

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

[0120] The chemical reactions in the blast furnace are mainly gas-solid phase reactions; from the perspective of microscopic reaction kinetics, the gas-solid phase reaction process includes the following stages: first, the gas phase reactants diffuse to the surface of the solid reactants, then they interact to form intermediate products, and finally, the intermediate products further react to form the final products. The kinetic models currently used to describe gas-solid phase reactions mainly include volume models, random pore models, and unreacted core shrinkage models.

[0121] Step 6: In order to improve the accuracy of the model, a two-way calculation method is used 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 operation status of the blast furnace to achieve efficient and safe production. The carbon monoxide concentration gradually decreases from bottom to top, and the concentration on the central axis is usually higher than the concentration on the furnace wall. Compared with the accurate carbon monoxide composition field model obtained by using Fluent fluid dynamics calculation software in other studies, it is obvious that the distribution of carbon monoxide concentration 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 cost. The algorithm for calculating the carbon monoxide concentration field proposed in this embodiment takes only 0.374 seconds on a computer equipped with an Intel 13700KF CPU, such as 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 calculation time and meets the ironmaking industry's demand for a fast digital twin model.

[0122] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the embodiments of the present disclosure is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the above-mentioned inventive concept. For example, the above-mentioned features are replaced with the technical features with similar functions disclosed in the embodiments of the present disclosure (but not limited to) to form a technical solution.

Claims

1. A method for calculating carbon monoxide composition field in a blast furnace based on digital twin, characterized in that: The following steps are involved: Step 1: Use the unreacted core shrinkage model to describe the gas-solid reaction process; Step 2: Calculate the blast furnace chemical reaction; Step 3: Generate the blast furnace modeling area. The mesh of the modeling area is generated using elliptic partial differential equations. The Navier-Stokes equations, or NS equations, describe the fluid flow in fluid mechanics. The NS equations are simplified to a two-dimensional form, and the fluid in the blast furnace is considered to be incompressible. The two-dimensional NS equations are discretized and solved to derive the velocity and pressure fields inside the blast furnace; Step 4: Calculate the reaction rate, assuming that in a defined region, when multiple carbon chemical reactions occur simultaneously, the consumption rate of carbon monoxide is equal to the algebraic sum of the corresponding reaction rates; Step 5: Assuming that the chemical properties of the reactants in each subspace of the blast furnace are uniform, the gas composition at the injection port is taken as input and the gas composition at the top is taken as output. A composition field model is constructed 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 variation along the gas path; Step 6: A bidirectional calculation method is used for the composition field model to calculate the carbon monoxide concentration at the furnace top layer by layer from top to bottom, and then calculate the carbon monoxide concentration at the furnace bottom from bottom to bottom; the results of these two calculations are averaged to obtain the final composition field model; the composition field calculation is performed through the composition field model to obtain the current blast furnace operation status.

2. The method for calculating carbon monoxide composition field of a blast furnace based on digital twin according to claim 1 is characterized in that: The step 1 is specifically as follows: Assuming that the solid reactant is composed of tiny spherical particles, the gas surrounds these particles and promotes the chemical reaction, wherein the chemical reaction only occurs on the surface where the reactants are in contact, and as the reaction proceeds, the reaction interface gradually shrinks; considering the effect of mass transfer resistance on the reaction rate, especially the resistance encountered by the outer gas when penetrating the spherical shell to react with the unreacted core material, the relationship between the obtained reaction rates is expressed as: 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.

3. The method for calculating carbon monoxide composition field of a blast furnace based on digital twin according to claim 1 is characterized in that: The step 2 is specifically as follows: Calculate the complete combustion chemical reaction of carbon. The specific chemical equation is: C+O2=CO2 (2) In the absence of sufficient oxygen, carbon will undergo incomplete combustion, and the chemical equation is: 2C+O2=2CO (3) The Arrhenius empirical formula establishes a mathematical relationship between the reaction rate and the reaction environment temperature. The equation describes the relationship between temperature and reaction rate as follows: In the formula, r represents the reaction rate, x and y represent the reactants and products respectively, c represents the concentration of the substance, 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 form carbon monoxide; the reaction is represented by the following equation: 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 is the initial carbon content of the coke, is the number of coke particles per square meter, M c is the molar mass of the gas, P T is the total pressure, γCO2, γCO, γH2O represent the mole fractions of carbon dioxide, carbon monoxide and water vapor, respectively, and t is the reaction time; The reaction equation for the conversion of iron oxide FeO into ferrite at high temperature is: FeO+C=Fe+CO (12) The reaction rate is expressed as: Among them, T s is the solid temperature, is the mole fraction of FeO, d s is the solid particle diameter, ψ s is the solid shape factor, ε s is the charge porosity; The unreacted shrinking core model is used to describe the indirect reduction of iron oxide, and the equation is as follows: Fe2O3+3CO=2Fe+3CO2 (17) In order to quantify the whole process of reducing spherical iron oxide particles using reducing gas, three reaction process levels are considered: gas film diffusion, that is, the gas does not contact the ore; diffusion inside the ore particles; and chemical reactions occurring at the reaction interface. By integrating the 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 is the equilibrium constant of the reaction, Ds 11 represents the gas diffusion efficiency, 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 pressure of carbon monoxide, and fs is the degree of reduction of iron ore.

4. The method for calculating carbon monoxide composition field of a blast furnace based on digital twin according to claim 1 is characterized in that: Step 3 is as follows: the temperature measured by infrared thermocouples at the temperature measurement points near the nozzle and the furnace top is used as the initial condition, and the temperature field of the blast furnace is obtained by bidirectional iterative solution using the discretized heat conduction differential equation.

5. The method for calculating carbon monoxide composition field of a blast furnace based on digital twin according to claim 4 is characterized in that: The bidirectional iteration is specifically as follows: iterative calculation is performed from the nozzle to the furnace top and from the furnace top to the nozzle respectively, and then weighted summation is performed.

6. The method for calculating carbon monoxide composition field of a blast furnace based on digital twin according to claim 1 is characterized in that: Step 4 is as follows: For chemical reactions involving gases in the blast furnace, the reaction time of the gases involved in these reactions is calculated using the following formula: Where treatment is the gas reaction time and Vgas is the gas flow rate.

7. The method for calculating carbon monoxide composition field of a blast furnace based on digital twin according to claim 1 is characterized in that: The CO concentration change described in step 5 is calculated by the reaction rate and the gas residence time. The CO concentration measured at the furnace top provides the boundary condition, 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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