Simulation method for coal powder and coke co-combustion in blast-furnace tuyere rotation area

Abstract

A simulation method for coal dust and coke co-combustion in a tuyere convolute area of a blast furnace belongs to the technical field of computer simulation, and comprises the following steps: step 1, drawing a 1 / n three-dimensional geometric model of the blast furnace by using modeling software, and exporting a corresponding STL (Standard Template Library) file; 2, importing the STL file into software with a DEM model, applying a circumferential periodic boundary condition, and establishing motion, heat transfer and reaction control equations of coke particles; and 3, importing the STL file into software with a CFD model, applying a circumferential periodic boundary condition, establishing a control equation of a gas phase, and establishing a motion control equation of pulverized coal by adopting a DPM model in the software with the CFD model. According to the method, the DEM-CFD-DPM coupling model is established to describe reaction flow and interaction of gas, coke particles and pulverized coal in the tuyere rotation area, and prediction of the size of the industrial-grade blast furnace rotation area and gas components in the furnace is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of computer simulation, and particularly relates to a simulation method for co-combustion of pulverized coal and coke in the tuyere raceway of a blast furnace. Background Art

[0002] A blast furnace is an important device for converting iron ore into metallic iron and is crucial for the steel industry. However, due to its high operating temperature and large volume, the blast furnace has extremely high energy consumption and becomes a major greenhouse gas emitter. Statistical data shows that 7% of the total global carbon dioxide emissions come from ironmaking, with the blast furnace accounting for 90% of the carbon dioxide emissions and over 70% of the energy consumption. Therefore, optimizing the production operation of the blast furnace is crucial for reducing energy consumption and pollution. In the lower part of the blast furnace, hot air is blown with pulverized coal onto the coke bed to form a tuyere raceway. Since coke and pulverized coal co-combust to provide the required heat and reducing gases for the reduction and melting processes in the upper part, the formation of the raceway is crucial for blast furnace operation. In addition, a higher coal combustion efficiency can reduce the carbon consumption of the blast furnace. Therefore, an in-depth understanding of the thermochemical behavior and dynamic evolution of the raceway is very critical for the low-carbon operation of the blast furnace.

[0003] Currently, the main simulation methods for raceway dynamics include the two-fluid model and the discrete element - computational fluid dynamics DEM-CFD model. Since the two-fluid model is limited in obtaining particle-scale information, many algorithms are developed based on the DEM-CFD model. However, currently, most models are only based on the combustion of coke in a pseudo-two-dimensional blast furnace raceway at the laboratory stage and still cannot fully reveal the dynamic behavior of the raceway in a three-dimensional industrial blast furnace. Moreover, the current models for simulating the raceway at the particle scale do not simultaneously consider the co-combustion behavior of coke and pulverized coal. Summary of the Invention

[0004] In view of the above-mentioned disadvantages and deficiencies of the prior art, the present invention provides a simulation method for co-combustion of pulverized coal and coke in the tuyere raceway of a blast furnace, and establishes a DEM-CFD-DPM coupling model to describe the reaction flow and interaction of gas, coke particles, and pulverized coal in the tuyere raceway, so as to achieve the prediction of the size of the industrial-level blast furnace raceway and the gas components in the furnace, and accurately calculate the evolution of parameters such as coke size, temperature, kinetic energy, and pulverized coal burnout rate.

[0005] To achieve the above object, the main technical solutions adopted by the present invention include:

[0006] A simulation method for co-combustion of pulverized coal and coke in the tuyere raceway of a blast furnace, comprising the following steps: Step 1: Use modeling software to draw a 1 / n three-dimensional geometric model of the blast furnace, where n is the number of tuyeres of the blast furnace, so that the model covers the furnace waist, furnace belly, and hearth parts of the blast furnace, and export the corresponding STL file; Step 2: Import the STL file from Step 1 into the software with the DEM model, and apply circumferential periodic boundary conditions on two sides of the model. Any particle leaving the boundary plane will enter the opposite plane, and the motion characteristics of the particles will rotate according to the angle difference between the two planes; conduct industrial analysis on the coke particle size using a particle size analyzer, define coke particle types of different sizes based on the analysis results, establish the control equations for the motion, heat transfer, and reaction of coke particles, and generate the initial coke bed layer. Step 3: Import the STL file from Step 1 into the software with the CFD model, set the same computational domain as the DEM software, use the mesh generation tool to mesh the three-dimensional geometric model of the blast furnace, and apply circumferential periodic boundary conditions on two sides of the model. Any gas component leaving the boundary plane will enter the opposite plane, and the thermal physical properties of the gas will rotate according to the angle difference between the two planes; establish the control equations for the gas phase, including the continuity equation, momentum equation, energy equation, and component transport model; establish the motion control equation for pulverized coal using the DPM model in the software with the CFD model. Step 4: Set the thermal physical properties, initial conditions, and boundary conditions of coke particles, pulverized coal, and gas in the software with the DEM model and the software with the CFD model. Step 5: Set the coupling module of the DEM model - CFD model - DPM model. Suppose it is completed within N times of Δt DEM time for the contact detection, collision dynamics calculation, and motion trajectory update of coke particles, where N is the time step Δt of the DEM model operation DEM which is a multiple smaller than the time step Δt of the CFD model operation CFD Then, map the key physical quantities of the coke particle phase, including at least position, velocity, and particle size, to the CFD grid nodes through the interpolation algorithm, calculate and update the particle / vacancy volume fraction of the CFD grid cell according to the coke particle position information, calculate the turbulence model and solve the flow heat transfer and reaction behavior between phases (i.e., gas - coke / pulverized coal) or within a phase (i.e., gas - gas), so as to calculate the coke particle / pulverized coal velocity, force, and temperature information; then feedback the coke particle information to the DEM model to dynamically update the particle motion state; subsequently, start the calculation of the next time step of the DEM, and repeat this process until the simulation time ends, complete the numerical simulation of the gas - coke - powder multiphase transport behavior in the raceway of the blast furnace, and save the calculation data within the set time step. Step 6: Extract the velocity, force, position, and particle size of coke particles, and conduct analysis and visualization processing to evaluate the particle motion characteristics; extract the velocity field, concentration field, and component field of the gas, and evaluate the gas distribution and flow characteristics through data analysis and visualization processing; extract the information of pulverized coal, including at least size, position, and burnout rate, and conduct statistical analysis to evaluate the burnout rate of pulverized coal.

[0007] Further, in the step 1, a 1 / 16 three-dimensional geometric model of the blast furnace is drawn using modeling software.

[0008] Further, in the step 2, the motion equation of the coke particles is as follows: (1); (2); Where: m pi is the mass of coke particle i, kg; v pi is the translational velocity of coke particle i, m / s; t is time, s; w pi is the angular velocity of coke particle i, rad / s; F d,pi is the drag force on coke particle i, N; F LS,pi is the Saffman lift force on coke particle i, N; F LM,pi is the Magnus lift force on coke particle i, N; F c,pij is the contact force between coke particles i and j, N; g is the acceleration due to gravity, m / s 2 ; I pi is the moment of inertia of coke particle i, kg·m 2 ; T pij is the torque exerted by coke particle j on coke particle i, N·m.

[0009] Further, in the step 2, the heat transfer equation of the coke particles is as follows: (3); Where: m pi is the mass of coke particle i, kg; c pi is the specific heat capacity of coke particle i, J / (kg·K); T pi is the temperature of coke particle i, K; h ij is the thermal conductivity between coke particles i and j, W / (m·K); dT pij / dn is the temperature gradient per unit length, K / m; A ij is the surface area of the coke particle, m 2 ; T g is the gas temperature, K; T pj is the temperature of coke particle j, K; T rad,g is the ambient temperature, K; h pi,conv is the convective heat transfer coefficient of coke particle i, W / (m 2 ·K); A pi is the surface area of coke particle i, m 2 ; σ is the Stefan-Boltzmann constant, W / (m 2 ·K4 ), ε p is the emissivity of the coke particle; q pi,reac is the heat flux generated by the chemical reaction of coke particle i, W.

[0010] Furthermore, in the step 2, the reaction control equation of the coke particle is as follows: (4); (5); where: D0 is the diffusion rate, mol / (m 2 ·s); C3 is the diffusion rate constant; T pi is the temperature of coke particle i, K; T g is the gas temperature, K; d pi is the diameter of the coke particle, m; R is the kinetic rate, kg·mol / (m 3 ·s); C4 is the pre-exponential factor, s -1 ; E is the activation energy, J / mol; R1 is the gas constant, 8.314 J / (mol·K); Weight the kinetic rate and the diffusion rate to obtain the reaction rate of the coke particle: (6); where: m pi is the mass of coke particle i, kg; A pi is the surface area of coke particle i, m 2 ; p ox is the partial pressure of the oxidant in the gas around the coke, Pa.

[0011] Furthermore, in the step 3, the continuity equation and the momentum equation are as follows: (7); (8); where: ε g is the local void fraction; ρ g is the gas density, kg / m 3 ; u g is the gas velocity, m / s; S mf is the gas component source term generated by the chemical reaction, kg / (m 3 ·s); p is the static pressure, Pa; τ is the stress tensor, Pa; F pf is the interaction force between the gas and the particle, N.

[0012] Furthermore, in the step 3, the energy equation and the component transport model are as follows: (9); (10); Where: ε g is the local void fraction; ρ g is the gas density, kg / m 3 ; u g is the gas velocity, m / s; T g is the gas temperature, K; c g is the specific heat capacity of the gas, J / (kg·K); k g is the thermal conductivity of the gas, W / (m·K); Q g,i , Q g,wall , Q reac , Q rad is the heat convection between the gas and the particles, the heat convection between the gas and the wall, the heat flux of chemical reaction, and the heat flux of radiation, W; V is the grid volume, m 3 ; C m is the mass fraction of the gas component; Γ m is the diffusion coefficient of gas component m, m 2 / s; S m is the chemical reaction source term, kg / (m 3 ·s).

[0013] Furthermore, in the step 3, the motion control equation of the pulverized coal includes: (11); (12); Where: m ci is the mass of pulverized coal particle i, kg; v ci is the translational velocity of pulverized coal particle i, m / s; t is time, s; w ci is the angular velocity of pulverized coal particle i, rad / s; F d,ci is the drag force on pulverized coal particle i, N; I ci is the moment of inertia of pulverized coal particle i, kg·m 2 ; T cij is the torque exerted by pulverized coal particle j on pulverized coal particle i, N·m.

[0014] Furthermore, in the step 3, the motion control equation of the pulverized coal also includes: (13); Where: c ci is the specific heat capacity of pulverized coal particle i, J / (kg·K); T ci is the temperature of pulverized coal particle i, K; h ci,conv is the convective heat transfer coefficient of pulverized coal particle i, W / (m 2·K); σ is the Stefan-Boltzmann constant, W / (m 2 ·K 4 ), T g is the gas temperature, K; A ci is the surface area of pulverized coal particle i, m 2 ; ε c is the emissivity of the pulverized coal particle; T rad,g is the ambient temperature, K; q ci,reac is the heat flux generated by the chemical reaction of pulverized coal particle i, W.

[0015] The beneficial effects of the present invention are as follows: By applying circumferential periodic boundary conditions to the side of the blast furnace in the DEM model and the CFD model, the present invention reduces the consumption of simulation resources, thereby ensuring the simulation of the entire furnace while reducing the actual computational amount, making it possible to simulate large blast furnaces.

[0016] By constructing a DEM-CFD-DPM coupled model, the present invention accurately simulates the co-combustion behavior of coke and pulverized coal in the raceway of the blast furnace at the particle scale, overcoming the limitations of traditional two-fluid models and pseudo-two-dimensional discrete element method-computational fluid dynamics models in obtaining particle-scale information and simulating the dynamics of three-dimensional industrial blast furnaces. This model can comprehensively consider the co-combustion process of coke and pulverized coal, accurately predict the size (depth, height, and width) of the raceway, the gas components in the furnace, and accurately calculate the dynamic evolution of key parameters such as the size, temperature, kinetic energy of coke, and burnout rate of pulverized coal. Through in-depth understanding of the thermochemical behavior and dynamic evolution of the blast furnace raceway, this model provides a scientific basis for optimizing blast furnace operation, helping to achieve a more efficient combustion process, reduce energy consumption and carbon emissions. In addition, this model can be applied to blast furnaces of different industrial levels, improving the reliability and feasibility of actual operation, and thus providing technical support for the green and low-carbon production of the steel industry. The model of the present invention can be applied to three-dimensional industrial blast furnaces to provide more comprehensive and accurate predictions of kinetic behavior. Brief Description of the Drawings

[0017] Figure 1 is a schematic diagram of the raceway of the blast furnace tuyere; Figure 2 is a schematic diagram of the process flow of the simulation method for co-combustion of pulverized coal and coke in the raceway of the blast furnace tuyere of the present invention; Figure 3 is a schematic diagram of the full-scale geometric model and 1 / 16 model of the blast furnace below the bosh; Figure 4 is a schematic diagram of the application of the circumferential periodic boundary in the DEM model; Figure 5 is a schematic diagram of the initial coke bed; Figure 6 is a distribution diagram of coke size; Figure 7 Schematic diagram of CFD grid division and circumferential periodic boundary for a three-dimensional blast furnace Figure 8 Schematic diagram of gas component distribution Figure 9 Evolution diagram of coke particle size and temperature over time Figure 10 Schematic diagram of spatial distribution of coke particle size Figure 11 Schematic diagram of spatial distribution of coke particle temperature Figure 12 Schematic diagram of spatial distribution of pulverized coal size Figure 13 Schematic diagram of spatial distribution of pulverized coal velocity Figure 14 Schematic diagram of the cavity in the raceway Figure 15 Distribution diagram of the depth, height and width of the raceway Detailed implementation manners

[0018] For better explaining the present invention for easy understanding, the present invention will be described in detail below in conjunction with the drawings through specific implementation manners

[0019] As shown in Figure 1 a blast furnace is a complex system combining physical processes and chemical reactions. As the direct power source for blast furnace smelting, the raceway is formed in the lower area of the blast furnace. Hot air and pulverized coal are injected into the coke bed through tuyeres and coal pipes, thus forming a cavity. In this area, heterogeneous reactions occur between coke and gas, devolatilization reactions and combustion reactions of volatile matter / fixed carbon occur to the pulverized coal, and interfacial reactions also occur between gas phases. Therefore, in order to more clearly analyze the co-combustion process of coke and pulverized coal in the dynamic raceway of an iron-making blast furnace, and thus provide a theoretical basis for optimizing blast furnace operation. The present invention establishes a DEM-CFD-DPM coupling model based on the particle scale to describe the reaction flow and its interaction of gas, coke particles, and pulverized coal (gas-carbon-powder) in the raceway

[0020] The present invention provides a simulation method for co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere, as shown in Figure 2 and includes the following steps A simulation method for co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere includes the following steps Step 1: Use modeling software to draw a 1 / n three-dimensional geometric model of the blast furnace, where n is the number of tuyeres of the blast furnace, ensure that the model covers the bosh, belly and hearth parts of the blast furnace, and export the corresponding STL file. Taking a 450m 3 blast furnace equipped with 16 tuyeres as an example: n = 16, as shown in Figure 3 and

[0021] Step 2: Import the STL file in Step 1 into the software with a DEM model. Specifically, the open-source software LIGGGHTS can be used. The area included in the geometric file is the calculation domain of the DEM model, and circular periodic boundary conditions are applied to both sides of the model. Any particle leaving the boundary plane will enter the opposite plane, and the motion characteristics of the particles, including force, torque, position, and velocity, will rotate according to the angle difference between the two planes. Conduct an industrial analysis of the coke particle size using a particle size analyzer, define different types of coke particles with different sizes based on the analysis results, establish the motion, heat transfer, and reaction control equations of the coke particles, and generate an initial coke bed. The schematic diagram of the application of the circular periodic boundary in the DEM model and the initial coke bed are as shown in Figure 4-5 shown. The particle size analysis of the coke particles is as shown in Figure 6 shown.

[0022] In Step 2 described above, the motion equation of the coke particles is as follows: The translational and rotational motions of the coke particles are controlled by Newton's second law: (1); (2); Where: m pi is the mass of coke particle i, kg; v pi is the translational velocity of coke particle i, m / s; t is time, s; w pi is the angular velocity of coke particle i, rad / s; F d,pi is the drag force on coke particle i, N; F LS,pi is the Saffman lift force on coke particle i, N; F LM,pi is the Magnus lift force on coke particle i, N; F c,pij is the contact force between coke particles i and j, N; g is the acceleration due to gravity, m / s 2 ; I pi is the moment of inertia of coke particle i, kg·m 2 ; T pij is the torque exerted by coke particle j on coke particle i, N·m.

[0023] The heat transfer equation of the coke particles, including the energy conservation equation acting on coke particle i, is as follows: (3); Where: m pi is the mass of coke particle i, kg; c pi is the specific heat capacity of coke particle i, J / (kg·K); T pi is the temperature of coke particle i, K; h ijis the thermal conductivity of coke particles i and j, W / (m·K); dT pij / dn is the temperature gradient per unit length, K / m; A ij is the surface area of the coke particle, m 2 ; T g is the gas temperature, K; T pj is the temperature of coke particle j, K; T rad,g is the ambient temperature, K; h pi,conv is the convective heat transfer coefficient of coke particle i, W / (m 2 ·K); A pi is the surface area of coke particle i, m 2 ; σ is the Stefan-Boltzmann constant, W / (m 2 ·K 4 ), ε p is the emissivity of the coke particle; q pi,reac is the heat flux generated by the chemical reaction of coke particle i, W, which is related to the enthalpy difference between the product and the reactant.

[0024] The combustion reaction of coke particles is described by a kinetic / diffusion rate model, mainly considering the following combustion reactions: C + O2 → CO2; 2C + O2 → 2CO; C + CO2 → 2CO; C + H2O → CO + H2; The rate of the combustion reaction depends on the diffusion rate D0 and the kinetic rate R.

[0025] The reaction control equation of coke particles is as follows: (4); (5); where: D0 is the diffusion rate mol / (m 2 ·s); C3 is the diffusion rate constant; T pi is the temperature of coke particle i, K; T g is the gas temperature, K; d pi is the coke particle diameter, m; R is the kinetic rate, kg∙mol / (m 3 ·s); C4 is the pre-exponential factor, s -1 ; E is the activation energy, J / mol; R1 is the gas constant, 8.314 J / (mol·K).

[0026] The kinetic rate and the diffusion rate are weighted to obtain the reaction rate of coke particles: (6); where: mpi is the mass of coke particle i, kg; A pi is the surface area of coke particle i, m 2 ; p ox is the partial pressure of the oxidant in the gas around the coke, Pa.

[0027] Step 3: Import the STL file of Step 1 into the software with a CFD model. Specifically, the Openform open-source software can be used. Set the same calculation domain as the DEM software, use the mesh generation tool to mesh the three-dimensional geometric model of the blast furnace, apply the circumferential periodic boundary condition to the two sides of the model, and any gas component leaving the boundary plane will enter the opposite plane. The thermal physical parameters of the gas, including velocity and pressure gradient, rotate according to the angle difference between the two planes; establish the control equations for the gas phase, including the continuity equation for describing the mass conservation of the gas phase; the momentum equation for describing the momentum conservation of the gas phase; the energy equation for describing the energy conservation of the gas phase; the component transport model for describing the transport and reaction processes between gas components; and use the DPM model in the software with a CFD model to establish the motion control equation of the pulverized coal.

[0028] The present invention applies the circumferential periodic boundary condition to the DEM model and the CFD model, thereby ensuring the simulation of the entire furnace while reducing the actual calculation amount, making it possible to simulate a large blast furnace.

[0029] Mesh generation of the three-dimensional blast furnace and the circumferential periodic boundary are as Figure 7 shown. The control equations for the gas phase include the continuity equation, the momentum equation, the energy equation, and the component transport model.

[0030] The continuity equation and the momentum equation are as follows: (7); (8); where: ε g is the local porosity; ρ g is the gas density, kg / m 3 ; u g is the gas velocity, m / s; S mf is the source term of the gas component generated due to chemical reaction, kg / (m 3 ·s); p is the static pressure, Pa; τ is the stress tensor, Pa; F pf is the interaction force between the gas and the particles, N.

[0031] The energy equation and the component transport model are as follows: (9); (10); where: ε g is the local void fraction; ρ g is the gas density, kg / m 3 ; u g is the gas velocity, m / s; T g is the gas temperature, K; c g is the specific heat capacity of the gas, J / (kg·K); k g is the thermal conductivity of the gas, W / (m·K); Q g,i , Q g,wall , Q reac , Q rad are the convective heat transfer between the gas and the particles, the convective heat transfer between the gas and the wall, the heat flux of chemical reaction, and the radiative heat flux, W; V is the grid volume, m 3 ; C m is the mass fraction of the gas component; Γ m is the diffusion coefficient of gas component m, m 2 / s; S m is the chemical reaction source term, kg / (m 3 ·s).

[0032] The motion equation of pulverized coal particles is controlled by Newton's second law. The motion control equations of pulverized coal include: (11); (12); where: m ci is the mass of pulverized coal particle i, kg; v ci is the translational velocity of pulverized coal particle i, m / s; t is time, s; w ci is the angular velocity of pulverized coal particle i, rad / s; F d,ci is the drag force on pulverized coal particle i, N; I ci is the moment of inertia of pulverized coal particle i, kg·m 2 ; T cij is the torque exerted by pulverized coal particle j on pulverized coal particle i, N·m.

[0033] The energy conservation equation for pulverized coal particle i is: (13); where: c ci is the specific heat capacity of pulverized coal particle i, J / (kg·K); T ci is the temperature of pulverized coal particle i, K; h ci,conv is the convective heat transfer coefficient of pulverized coal particle i, W / (m 2 ·K); σ is the Stefan-Boltzmann constant, W / (m 2 ·K 4), T g is the gas temperature, K; A ci is the surface area of pulverized coal particle i, m 2 ; ε c is the emissivity of the pulverized coal particle; T rad,g is the ambient temperature, K; q ci,reac is the heat flux generated by the chemical reaction of pulverized coal particle i, W, which is related to the enthalpy difference between the product and the reactant.

[0034] The chemical process of pulverized coal mainly considers the following reactions: coal devolatilization to produce fixed carbon and volatile matter; Volatiles + O2 → CO + N2 + H2O + SO2; C + O2 → CO2; 2C + O2 → 2CO; C + CO2 → 2CO; C + H2O → CO + H2.

[0035] Step 4: Set the thermal physical properties, initial conditions, and boundary conditions of coke particles, pulverized coal, and gas in the software with the DEM model and the software with the CFD model. The thermal physical properties, initial conditions, and boundary conditions of coke particles, pulverized coal, and gas are shown in Table 1.

[0036] Table 1. Physical property parameters, initial conditions, and boundary conditions used in the simulation .

[0037] Step 5: Set the coupling module of the DEM model - CFD model - DPM model; In the gas - solid two - phase flow, the gas flow distribution in the CFD model affects the particle motion in the DEM model, and vice versa. Therefore, a DEM - CFD two - way coupling module needs to be constructed to achieve high - precision analysis of the inter - phase dynamic interaction. Considering that the time step Δt of the DEM model DEM is usually N times smaller than the time step Δt of the CFD operation CFD , where N generally ranges from 5 to 100, the following coupling strategy is adopted. Suppose the contact detection, collision dynamics calculation, and motion trajectory update of coke particles are completed within N times of Δt DEM time, where N is the time step Δt of the DEM model operation DEM is smaller than the time step Δt of the CFD model operation CFDSmall multiples; then, key physical quantities of the coke particle phase, including at least position, velocity, and particle size, are mapped to CFD grid nodes through an interpolation algorithm. The particle / vacancy volume fraction of the CFD grid cells is calculated and updated based on the coke particle position information, and the turbulent model is calculated and the flow heat transfer and reaction behaviors between phases, i.e., gas-coke / coal powder or within a phase, i.e., gas-gas, are solved, so as to calculate the coke particle / coal powder velocity, forces, including drag force, Saffman lift force, and Magnus lift force, and temperature information; then the information of the coke particles is fed back to the DEM model to dynamically update the particle motion state; subsequently, the calculation of the next time step of the DEM is started, and so on until the simulation time ends, completing the numerical simulation of the gas-carbon-powder multiphase transport behavior in the BF raceway region, and saving the calculation data within the set time step. The present invention constructs a DEM-CFD-DPM model to describe the reaction flow and interaction of fluids, particles, and fine powders.

[0038] Specifically, the calculation time step Δt of the coke particles DEM is 1.5×10 -4 s, and the time step Δt of the fluid CFD is 7×10 -4 s, and the data file is saved according to the set time step as the saving interval.

[0039] Step 6: Extract the velocity, force, position, and particle size of the coke particles, and perform analysis and visualization processing. Visualization processing can be carried out using Tecplot software to evaluate the particle motion characteristics; extract the velocity field, concentration field, and component field of the gas, and evaluate the gas distribution and flow characteristics through data analysis and visualization processing; extract the information of the coal powder, including at least size, position, and burnout rate, and perform statistical analysis to evaluate the coal powder burnout rate.

[0040] Referring to a blast furnace with a volume of 450 m 3 in a certain steel plant, the area below the bosh of the blast furnace is simulated. Hot air and coal-carrying gas are injected into the tuyere and the coal pipe at flow rates of 50 m / s and 11.5 m / s respectively. The temperatures of the hot air and the coal-carrying gas are 1323 K and 333 K respectively, and the mass fraction of oxygen in the hot air is 0.27. The components of the coal-carrying gas are all N2. The gas parameters, coke parameters, and blast furnace size parameters are shown in Table 1. Figure 8 The gas component distribution in the furnace is analyzed, and it can be seen that the model can well predict the gas mass fraction in the raceway region. Figure 9-11 The evolution and spatial distribution of the coke particle size and coke temperature in the furnace are analyzed, and it can be seen that the coke size gradually becomes smaller with the reaction time, while the coke temperature gradually increases with the reaction time. Figure 12-13For the size distribution and velocity of pulverized coal, it can be seen that the velocity of the initial pulverized coal is very high when it is injected into the cavity of the raceway, while the velocity approaches zero when the pulverized coal is located in the dense area of the coke bed. Figure 14-15 The cavity of the raceway and its depth, height and width under the current embodiment are predicted. Through analysis, it can be seen that the model proposed by the present invention can well describe the reaction flow and interaction of gas, coke particles and pulverized coal in the blast furnace raceway.

[0041] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any modifications, alterations, substitutions and variations made by those of ordinary skill in the art to the above embodiments fall within the scope of the present invention.

[0042] In addition, it should be noted that the DEM-CFD-DPM model proposed by the present invention is not only applicable to simulating the process of the blast furnace raceway, but also applicable to the process involving gas-solid reactions, such as biomass combustion and other processes.

Claims

1. A simulation method for co - combustion of pulverized coal and coke in the raceway of a blast furnace tuyere, characterized in that, It includes the following steps: Step 1: Use modeling software to draw a 1 / n three-dimensional geometric model of the blast furnace, where n is the number of tuyeres of the blast furnace, so that the model covers the bosh, hearth and hearth parts of the blast furnace, and export the corresponding STL file; Step 2: Import the STL file of Step 1 into the software with a DEM model, and apply circumferential periodic boundary conditions on two sides of the model. Any particle leaving the boundary plane will enter the opposite plane, and the motion characteristics of the particles will rotate according to the angle difference between the two planes; Use a particle size analyzer to conduct an industrial analysis of the coke particle size, and define different sizes of coke particle types based on the analysis results, establish the motion, heat transfer, and reaction control equations of the coke particles, and generate an initial coke bed layer; Step 3: Import the STL file of Step 1 into the software with a CFD model, set the same calculation domain as the DEM software, use a mesh generation tool to mesh the three-dimensional geometric model of the blast furnace, and apply circumferential periodic boundary conditions on two sides of the model. Any gas component leaving the boundary plane will enter the opposite plane, and the thermal physical properties of the gas will rotate according to the angle difference between the two planes; Establish the control equations of the gas phase, including the continuity equation, momentum equation, energy equation, and component transport model; Use the DPM model in the software with a CFD model to establish the motion control equation of the pulverized coal; Step 4: Set the thermal physical properties, initial conditions and boundary conditions of the coke particles, pulverized coal and gas in the software with a DEM model and the software with a CFD model; Step 5: Set the coupling module of the DEM model - CFD model - DPM model; It is assumed that the contact detection of coke particles, the calculation of collision dynamics and the update of the movement trajectory are completed within N times of ∆t DEM where N is the time step ∆t of the DEM model operation DEM which is smaller than the time step ∆t of the CFD model operation CFD by a certain multiple; then, the key physical quantities of the coke particle phase, including at least position, velocity, and particle size, are mapped to the CFD grid nodes through an interpolation algorithm, and the particle / vacancy volume fraction of the CFD grid cells is calculated and updated according to the coke particle position information, and the turbulent model and the flow heat transfer and reaction behaviors between phases (i.e., gas-coke / coal powder) or within phases (i.e., gas-gas) are calculated, so as to calculate the coke particle / coal powder velocity, force, and temperature information; then the information of the coke particles is fed back to the DEM model to dynamically update the particle motion state; subsequently, the calculation of the next time step of the DEM is started, and so on until the simulation time ends, completing the numerical simulation of the gas-carbon-powder multiphase transport behavior in the BF raceway area, and saving the calculation data within the set time step; Step 6: Extract the velocity, force, position, and particle size of the coke particles, and perform analysis and visualization to evaluate the particle motion characteristics; Extract the velocity field, concentration field, and component field of the gas, and evaluate the gas distribution and flow characteristics through data analysis and visualization; Extract the information of the pulverized coal, including at least the size, position, and burnout rate, and perform statistical analysis to evaluate the burnout rate of the pulverized coal.

2. The simulation method for co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere according to claim 1, wherein: In Step 1, a 1 / 16 three-dimensional geometric model of the blast furnace is drawn using modeling software.

3. The simulation method of co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere according to claim 1, characterized in that: In Step 2, the motion equation of the coke particles is as follows: （1）； （2）； where: m pi is the mass of coke particle i, kg; v pi is the translational velocity of coke particle i, m / s; t is time, s; w pi is the angular velocity of coke particle i, rad / s; F d,pi is the drag force on coke particle i, N; F LS,pi is the Saffman lift force on coke particle i, N; F LM,pi is the Magnus lift force on coke particle i, N; F c,pij is the contact force between coke particles i and j, N; g is the acceleration due to gravity, m / s 2 ; I pi is the moment of inertia of coke particle i, kg·m 2 ; T pij is the torque exerted by coke particle j on coke particle i, N·m.

4. The simulation method of co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere according to claim 1, characterized in that: In Step 2, the heat transfer equation of the coke particles is as follows: （3）； Where: m pi is the mass of coke particle i, kg; c pi is the specific heat capacity of coke particle i, J / (kg·K); T pi is the temperature of coke particle i, K; h ij is the heat conduction coefficient between coke particles i and j, W / (m·K); dT pij / dn is the temperature gradient per unit length, K / m; A ij is the surface area of the coke particle, m 2 ; T g is the gas temperature, K; T pj is the temperature of coke particle j, K; T rad,g is the ambient temperature, K; h pi,conv is the convective heat transfer coefficient of coke particle i, W / (m 2 ·K); A pi is the surface area of coke particle i, m 2 ; σ is the Stefan-Boltzmann constant, W / (m 2 ·K 4 ), ε p is the emissivity of the coke particle; q pi,reac is the heat flux generated by the chemical reaction of coke particle i, W.

5. A simulation method for co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere, according to claim 1, characterized in that: In Step 2, the reaction control equation of the coke particles is as follows: （4）； （5）； Among them: D0 is the diffusion rate, mol / (m 2 ·s); C3 is the diffusion rate constant; T pi is the temperature of coke particle i, K; T g is the gas temperature, K; d pi is the diameter of the coke particle, m; R is the kinetic rate, kg∙mol / (m 3 ·s); C4 is the pre-exponential factor, s -1 ; E is the activation energy, J / mol; R1 is the gas constant, 8.314 J / (mol·K); Weight the kinetic rate and diffusion rate to obtain the reaction rate of the coke particles: （6）； Where: m pi is the mass of coke particle i, kg; A pi is the surface area of coke particle i, m 2 ; p ox is the partial pressure of the oxidant in the gas around the coke, Pa.

6. The simulation method for co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere according to claim 1, characterized in that: In Step 3, the continuity equation and momentum equation are as follows: （7）； （8）； where: ε g is the local void fraction; ρ g is the gas density, kg / m 3 ; u g is the gas velocity, m / s; S mf is the source term of gas components generated by chemical reactions, kg / (m 3 ·s); p is the static pressure, Pa; τ is the stress tensor, Pa; F pf is the interaction force between gas and particles, N.

7. The simulation method of co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere according to claim 1, characterized in that: In Step 3, the energy equation and component transport model are as follows: （9）； （10）； Where: ε g is the local void fraction; ρ g is the gas density, kg / m 3 ; u g is the gas velocity, m / s; T g is the gas temperature, K; c g is the specific heat capacity of the gas, J / (kg·K); k g is the thermal conductivity of the gas, W / (m·K); Q g,i , Q g,wall , Q reac , Q rad are the heat convection between the gas and the particles, the heat convection between the gas and the wall, the heat flux of chemical reaction, and the heat flux of radiation, respectively, W; V is the grid volume, m 3 ; C m is the mass fraction of the gas component; Γ m is the diffusion coefficient of gas component m, m 2 / s; S m is the chemical reaction source term, kg / (m 3 ·s).

8. A simulation method for co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere, according to claim 1, characterized in that: In Step 3, the motion control equation of the pulverized coal includes: （11）； （12）； where: m ci is the mass of pulverized coal particle i, kg; v ci is the translational velocity of pulverized coal particle i, m / s; t is time, s; w ci is the angular velocity of pulverized coal particle i, rad / s; F d,ci is the drag force on pulverized coal particle i, N; I ci is the moment of inertia of pulverized coal particle i, kg·m 2 ; T cij is the torque exerted by pulverized coal particle j on pulverized coal particle i, N·m.

9. A simulation method for co-combustion of pulverized coal and coke in the raceway of a blast furnace tuyere, according to claim 8, characterized in that: In Step 3, the motion control equation of the pulverized coal also includes: （13）； Where: c ci is the specific heat capacity of pulverized coal particle i, J / (kg·K); T ci is the temperature of pulverized coal particle i, K; h ci,conv is the convective heat transfer coefficient of pulverized coal particle i, W / (m 2 ·K); σ is the Stefan–Boltzmann constant, W / (m 2 ·K 4 ), T g is the gas temperature, K; A ci is the surface area of pulverized coal particle i, m 2 ; ε c is the emissivity of the pulverized coal particle; T rad,g is the ambient temperature, K; q ci,reac is the heat flux generated by the chemical reaction of pulverized coal particle i, W.

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