Particle deposition analysis method for water-cooling flue of submerged arc smelting furnace based on Fluent-UDF

Abstract

The invention relates to a particle deposition analysis method for a water-cooling flue of a smelting furnace, in particular to a particle deposition analysis method for a water-cooling flue of a submerged arc furnace based on Fluent-UDF, which comprises the following steps: establishing a geometric model of the water-cooling flue of the submerged arc furnace, and importing the model into an ICEM for structured grid division; according to the method, on the basis of an energy conservation deposition model and a critical collision angle model, an algorithm for transporting, depositing, rebounding and removing particles in the water-cooled flue is compiled by combining a user-defined function (UDF), so that a mathematical analysis model for particle scaling is established; the model considers the influence of the temperature in the water-cooled flue and the gravity, thermophoresis force, Saffman force, drag force, Brown force and inertia force on particle deposition in the particle transportation process. According to the method, the deposition position and the deposition quality of the particles can be accurately predicted, and an important basis is provided for optimizing flue design and operation conditions. Through the method, the flue gas recovery efficiency can be effectively improved, the service life of equipment is prolonged, and the maintenance cost is reduced.

Description

Technical Field

[0001] The present invention relates to a method for analyzing particle deposition in a water-cooled flue of a submerged arc furnace, and particularly to a method for analyzing particle deposition in a water-cooled flue of a submerged arc furnace based on Fluent-UDF. Technical Background

[0002] The rotary kiln-submerged arc furnace (RKEF) smelting process uses relatively inexpensive nickel ore as raw material to smelt nickel-iron alloy. Compared with the blast furnace smelting process, the product quality is better and the efficiency is higher. However, the RKEF process also has problems such as high energy consumption. To reduce energy consumption, the RKEF process recovers the reducing gas containing 75% CO generated by the closed submerged arc furnace. This gas is transported through a water-cooled flue to the rotary kiln and burned as fuel to provide the heat energy required by the rotary kiln, and the dust is returned to the submerged arc furnace to continue participating in the smelting. However, during the process of transporting the high-temperature furnace gas carrying a large amount of ore particles through the water-cooled flue to the rotary kiln, the ore particles will collide, rub and deposit on the inner wall of the water-cooled flue. The long-term collision of the ore particles with the inner wall of the water-cooled flue will increase particle deposition and block the water-cooled flue, reducing the service life of the water-cooled flue. Therefore, it is necessary to deeply study the mechanisms of particle transport, deposition, rebound and removal in the water-cooled flue to reduce particle deposition and ensure the safe and efficient transport of high-temperature furnace gas. Based on the RKEF nickel-iron smelting process, the present invention conducts a numerical study on the characteristics of particle transport, deposition, rebound and removal in the water-cooled flue of the submerged arc furnace, and develops a numerical simulation based on UDF compilation to simulate particle transport, deposition, rebound and removal in the water-cooled flue of the submerged arc furnace.

[0003] Researchers have found that particle deposition on the surface of equipment is affected by particle transport mechanisms. Particles are generally transported to the surface through mechanisms such as inertial collision, thermophoresis, condensation and turbulent diffusion. Therefore, the deposition methods of particles can be mainly divided into: inertial collision deposition, thermophoretic force collision deposition, eddy collision deposition, diffusion deposition, etc. Particle deposition depends not only on the transport mechanism but also on the relationship between the incident kinetic energy of the particle and the energy loss when it impacts the wall surface. The loss of incident kinetic energy is jointly affected by various physical mechanisms such as surface adhesion, elastic deformation, elastoplastic deformation, viscoelastic dissipation, etc.

[0004] Currently, the research on particle deposition mainly focuses on equipment such as heat exchangers and boilers. Many researchers have conducted in-depth studies on particle deposition characteristics through experimental and simulation methods, and certain achievements have been made in the research of mathematical models. However, there are still some deficiencies in the research on the mechanisms of particle transport, deposition, rebound, and removal in the large geometric-sized submerged arc furnace flue. During the transportation of flue gas, the particles mixed in the flue gas are prone to deposition in the flue, affecting the stability of flue gas transportation and the service life of equipment. The flue gas in the submerged arc furnace flue has a high temperature, a large temperature range change under the action of cooling water, and the particle size range of the ore particles carried in the flue gas is relatively large (5 - 140 μm). Therefore, in current production practices, there is an urgent need for a numerical method to accurately predict particle transport, deposition, rebound, and removal in the submerged arc furnace flue under actual working conditions. Summary of the Invention

[0005] The object of the present invention is to provide a method for analyzing particle deposition in the water-cooled flue of a submerged arc furnace based on Fluent-UDF. On the basis of the particle deposition model, the effects of temperature in the water-cooled flue and gravity, Saffman force, drag force, inertial force, thermophoretic force, and Brownian force on particle deposition during particle transport are considered. The particle fouling mass is obtained by calculating the particle deposition mass and removal mass.

[0006] The present invention adopts the following technical solutions:

[0007] A method for analyzing particle deposition in the water-cooled flue of a submerged arc furnace based on Fluent-UDF includes the following steps:

[0008] Step 1: Establish a geometric model of the water-cooled flue of the submerged arc furnace, import the model into ICEM for structured grid division, and import the grid model into the Fluent software for flow field analysis and calculation;

[0009] Step 2: Compile a model for particle transport, deposition, rebound, and removal in the water-cooled flue in combination with the user-defined function (UDF) and import it into the Fluent software;

[0010] Step 3: Set the gravity, energy, turbulence, and discrete phase models in sequence;

[0011] Step 4: Set the inlet boundary condition as velocity inlet, the outlet boundary condition as free outlet, and the inlet and outlet discrete phase boundary conditions as escape;

[0012] Step 5: Use the SIMPLE algorithm to handle the coupling relationship between velocity and pressure, and adopt the second-order upwind difference format for the continuity, momentum, and energy equations.

[0013] Preferably, the water-cooled flue is a device for transporting furnace gas containing CO components in the energy-saving process of the submerged arc furnace.

[0014] Preferably, the particle size follows the Rosin-Rammler distribution, with a particle size range of 5 - 140 μm, ignoring the interaction between particles during the transportation method and the effect of particles on the furnace gas.

[0015] Preferably, based on the particle size distribution characteristics, the main deposition methods of particles are inertial collision deposition, thermophoretic collision deposition, and eddy collision deposition.

[0016] The Lagrangian method and the particle force balance analysis are combined to predict the movement and trajectory of particles. When analyzing the forces acting on particles, the drag force, gravitational force, inertial force, Saffman force, thermophoretic force, and Brownian force of the particles are considered. The control equation for the particle trajectory is:

[0017] The right side of formula (1) represents the drag force, gravitational force, inertial force, Saffman force, thermophoretic force, and Brownian force respectively, u p The velocity of the particle; u 1 The flow velocity of the furnace gas; ρ p The density of the particle; ρ is the density of the furnace gas; m p The mass of the particle; τ r The expression for the relaxation time of the particle is as follows:

[0018]

[0019] In the formula, C D Is the drag coefficient; μ is the dynamic viscosity of the furnace gas; Re is the particle Reynolds number:

[0020] Re = ρd p |u p -u 1 | / μ.

[0021] When Re < 0.01, C D Is expressed as:

[0022]

[0023] When 0.01 ≤ Re < 20, C D Is expressed as:

[0024]

[0025] When Re > 20, C D Is expressed as:

[0026]

[0027] The Saffman force F saff The expression is as follows:

[0028]

[0029] In the formula, K C = 2.594, d ij is the deformation tensor.

[0030] The expression formula of the thermophoretic force is as follows:

[0031]

[0032] In the formula, μ is the gas dynamic viscosity; C s is a constant, C s = 1.17; C t is a constant, C t = 2.18; C m is a constant, C m = 1.14; m p is the particle mass; T is the fluid temperature; k p is the particle thermal conductivity; k is the gas thermal conductivity based on the translational kinetic energy of the gas, and the expression is:

[0033]

[0034] k n The expression of the Knudsen number is:

[0035]

[0036] In the formula, λ is the average gas molecular free path; d p is the particle radius.

[0037] The expression of the Brownian force is:

[0038]

[0039] In the formula, ξ is a Gaussian random number with an average value of 0 and a variance of 1; Δt is the time step used in the calculation; S 0 is the spectral intensity; T is the absolute temperature of the fluid; v is the kinematic viscosity of air; k b is the Boltzmann constant; C c is the correction to the Stokes drag law.

[0040] Preferably, the deposition and rebound model of the particles considers the elastic and elastoplastic deformations occurring during particle collisions and the influence of the incident kinetic energy, surface energy, and adhesion energy of the particles on deposition.

[0041] Preferably, the furnace gas generated by the submerged arc furnace is high-temperature gas, which is transported through a water-cooled flue. During the transportation process, the temperature of the furnace gas will fluctuate within a certain range (800K - 1100K) due to the influence of cooling water. The temperature fluctuation will affect the physical properties of the particles and the wall surface of the water-cooled flue, and further affect the particle deposition rate.

[0042] Preferably, the particle deposition model takes into account the influence of the temperature in the water-cooled flue on particle deposition.

[0043] Preferably, the particle deposition judgment condition is determined by the particle restitution coefficient e 2 , the incident angle θ and the critical angle θ cr jointly.

[0044] Preferably, the particle deposition model is compiled using the DEFINF_DPM_EROSION macro in the UDF subroutine.

[0045] Preferably, when the particle collides with the wall surface of the water-cooled flue, if e 2 < 0 and θ < θ cr , the particle will deposit and be stored in the UDM; otherwise, the particle will rebound and the particle rebound velocity will be calculated.

[0046] Preferably, energy conservation is followed when the particle impacts the wall surface of the water-cooled flue, and its expression is as follows:

[0047] Q i,n +Q A,a =Q el +Q pe +Q p (12)

[0048] In the formula, Q i,n is the kinetic energy of the incident particle, Q A,a is the surface energy of the particle, Q el and Q pe are the elastic strain energies stored in the elastic deformation zone and the plastic deformation zone respectively, Q p is the energy loss when the particle undergoes plastic deformation, and its expression is as follows:

[0049]

[0050]

[0051] E s =19.167758+0.001000158T 2 -0.000017T 2 2 (20)

[0052] In the formula, u i,nis the incident normal velocity; m is the particle mass; F is the contact load; y is the elastic load limit; R is the particle radius; E * is the effective Young's modulus; v s and v p represent the Poisson's ratios of the flue duct wall and the particle respectively; E s and E p represent the Young's moduli of the water-cooled flue duct wall and the particle respectively; T 1 and T 2 are the particle and flue duct wall temperatures; Γ represents the adhesion work; its expression is as follows:

[0053]

[0054] In the formula, γ 1 and γ 2 are the free energies of the particle and the flue duct wall respectively.

[0055] When the velocity of the particle hitting the water-cooled flue duct wall is zero, the kinetic energy is zero. The contact load F is solved according to Eqs. (12) to (21).

[0056] When the particle hits the water-cooled flue duct wall, if the particle normal velocity is less than the critical elastic velocity, the particle undergoes plastic deformation, otherwise the particle undergoes elastic deformation. The expression of the critical elastic velocity is as follows:

[0057]

[0058] In the formula, ρ is the particle density; c is the proportionality coefficient.

[0059] When the particle collides, the elastic deformations Q pe and Q p are zero. The expression of the particle restitution coefficient is as follows:

[0060]

[0061] When the particle rebounds, the elastic energy stored is converted into the particle kinetic energy, and the particle begins to move away from the water-cooled flue duct wall. The particle rebound velocity is:

[0062]

[0063] When the particle collides and undergoes plastic deformation, the expression of the particle restitution coefficient is as follows:

[0064]

[0065] When the particle rebounds, the elastic and plastic energies stored are converted into the particle kinetic energy, and the particle rebound velocity is:

[0066]

[0067] Preferably, when the incident angle of the particle is greater than the critical angle, the particle does not deposit, and the expression of the critical angle is as follows:

[0068]

[0069] In the formula, f * is the effective friction coefficient; β is the effective coefficient of the contact radius; ν p is the Poisson's ratio of the particle.

[0070] Preferably, the removal model described in step two is compiled by using the DEFINF_DPM_EROSION macro in the UDF subroutine. The removal rate of the particle is proportional to the particle deposition thickness and the wall shear stress, and inversely proportional to the deposition strength coefficient; the particle removal model introduces the wall shear stress and the particle deposition thickness to accurately simulate the particle removal behavior, and the expression of the removal rate is as follows:

[0071]

[0072] In the formula, k is the removal constant; ψ is the deposition layer strength coefficient; x f and τ w are the thickness of the particle deposition and the wall shear stress, and the expressions are:

[0073]

[0074]

[0075] In the formula, m f is the fouling mass per unit area; μ is the kinematic viscosity of the gas; u is the particle velocity.

[0076] Preferably, the deposition mass minus the removal mass is the fouling mass, and the expression is:

[0077]

[0078] In the formula, m r,t is the removal mass starting from time t; is the newly added removal mass within the time step Δt.

[0079] Preferably, the particle deposition model is established by using the UDF subroutine to call the DEFINE_DPM_EROSION macro. This technical solution not only compiles the particle restitution coefficient and the critical angle solution formula that vary with temperature to determine whether the particle deposits, but also compiles the algorithms for particle transport and removal, so as to accurately predict the collision, deposition and rebound behaviors of the particle with the water-cooled flue wall.

[0080] The beneficial effects of the present invention are:

[0081] A method for analyzing particle deposition in the water-cooled flue of a submerged arc furnace based on Fluent-UDF is proposed in the present invention. On the basis of the particle deposition model, the effects of gravity, inertial force, thermophoretic force, Saffman force, drag force, and Brownian force on particle deposition during the temperature and particle transport processes in the water-cooled flue are considered. The fouling mass of particles is obtained by calculating the deposition mass and removal mass of particles. The method of the present invention can accurately predict the deposition position and deposition mass of particles, providing an important basis for optimizing the flue design and operating conditions. Through this method, the flue gas recovery efficiency can be effectively improved, the service life of the equipment can be extended, and the maintenance cost can be reduced. Description of the Drawings

[0082] Figure 1 It is a schematic structural diagram of the water-cooled flue corresponding to a method for analyzing particle deposition in the water-cooled flue of a submerged arc furnace based on Fluent-UDF of the present invention;

[0083] Figure 2 It is a schematic flow diagram of a method for analyzing particle deposition in the water-cooled flue of a submerged arc furnace based on Fluent-UDF of the present invention;

[0084] Figure 3 It is a schematic flowchart of the UDF subroutine of a method for analyzing particle deposition in the water-cooled flue of a submerged arc furnace based on Fluent-UDF of the present invention;

[0085] Figure 4 It is a deposition cloud map of the water-cooled flue of a method for analyzing particle deposition in the water-cooled flue of a submerged arc furnace based on Fluent-UDF of the present invention. Detailed Embodiments

[0086] To make the objectives, technical solutions, and advantages of the present technical solution clearer and more understandable, the present technical solution will be further specifically described below in conjunction with the detailed embodiments:

[0087] As Figures 1 to 3 shown, it is a method for analyzing particle deposition in the water-cooled flue of a submerged arc furnace based on Fluent-UDF, including the following:

[0088] As Figure 2 Establish a geometric model of the water-cooled flue of the submerged arc furnace, import the model into ICEM for unstructured grid division, and then import the grid model into the Fluent software; set the gravity, turn on the energy equation, adopt the RNG k-epsilon turbulence model, turn on the discrete phase model, and the particle size follows the Rosin-Rammler distribution; compile a model for particle transport, deposition, rebound, and removal in the flue in combination with the user-defined function (UDF), and import it into the Fluent software for flow field analysis and calculation; the particle size range is 5-140 μm, and the interaction between particles in the transportation method and the effect of particles on the furnace gas are ignored. As Figure 1As shown in the figure: The high-temperature furnace gas carrying a large amount of ore particles enters the flue from the bottom, passes through the furnace mouth section, the first-section flue, the second-section flue, the third-section flue, the three-way section, and the blind pipe section in sequence, and finally flows out from the outlet section. The cooling water flows in from the water-cooling inlet and out from the outlet.

[0089] As Figure 3 shown, the numerical simulation of a UDF subroutine flowchart for simulating particle deposition in a water-cooled flue of a submerged arc furnace is as follows:

[0090] First, the UDF subroutine for analyzing the forces acting on particles during the particle transport process is written. By combining the Lagrangian method and the particle force balance analysis, the motion trajectory of the particles is predicted. When analyzing the forces acting on the particles, the drag force, gravitational force, inertial force, Saffman force, thermophoretic force, and Brownian force of the particles are considered. The control equation for the particle trajectory:

[0091]

[0092] The right side of formula (1) is the drag force, gravitational force, inertial force, Saffman force, thermophoretic force, and Brownian force respectively. u p is the velocity of the particle; u 1 is the flow velocity of the furnace gas; ρ p is the particle density; ρ is the furnace gas density; m p is the mass of the particle; τ r The expression for the relaxation time of the particle is as follows:

[0093]

[0094] In the formula, C D is the drag coefficient; μ is the dynamic viscosity of the furnace gas; Re is the particle Reynolds number, Re = ρd p |u p −u 1 | / μ.

[0095] When Re < 0.01, C D is expressed as:

[0096]

[0097] When 0.01 ≤ Re < 20, C D is expressed as:

[0098]

[0099] When Re > 20, C D is expressed as:

[0100]

[0101] The Saffman force Fsaff The expression is as follows:

[0102]

[0103] In the formula, K C = 2.594, d ij is the deformation tensor.

[0104] The expression formula of the thermophoretic force is as follows:

[0105]

[0106] In the formula, μ is the dynamic viscosity of the gas; C s is a constant, C s = 1.17; C t is a constant, C t = 2.18; C m is a constant, C m = 1.14; m p is the particle mass; T is the fluid temperature; k p is the particle thermal conductivity; k is the gas thermal conductivity based on the translational kinetic energy of the gas, and the expression is:

[0107]

[0108] k n is the expression of the Knudsen number as:

[0109]

[0110] In the formula, λ is the average free path of gas molecules; d p is the particle radius.

[0111] The expression of the Brownian force is:

[0112]

[0113] In the formula, ξ is a Gaussian random number with an average value of 0 and a variance of 1; Δt is the time step used in the calculation; S 0 is the spectral intensity; T is the absolute temperature of the fluid; v is the kinematic viscosity of air; k b is the Boltzmann constant; C c is the correction to the Stokes drag law.

[0114] Secondly, the UDF subroutine is used to call the DEFINE_DPM_EROSION macro to write the particle deposition judgment criterion, that is, using the particle restitution coefficient e 2 , the incident angle θ and the critical angle θ crDetermine whether particle deposition occurs. In this technical solution, the furnace gas generated by the submerged arc furnace is a high-temperature gas, which is transported through a water-cooled flue. During the transportation process, the temperature of the furnace gas will fluctuate within a certain range (800K - 1100K) due to the influence of cooling water. The temperature fluctuation causes changes in the physical properties of the particles and the flue wall. Therefore, the particle deposition model takes into account the influence of the temperature in the water-cooled flue on the physical properties of the particles and the flue wall. Compared with other solutions, this solution is more in line with the deposition behavior under actual working conditions. When the particles collide with the wall of the water-cooled flue, if e 2 <0 and θ < θ cr , the particles will deposit on the wall of the water-cooled flue; otherwise, the particles will rebound from the wall of the water-cooled flue. This technical solution uses user-defined memory (UDM) to store the number of particles deposited on the wall of the water-cooled flue. The initial value of UDM at the start of the calculation is zero. As the particles are injected, the number of deposited particles will be stored in UDM0, which is the deposited mass m d .

[0115] When the particles impact the wall of the water-cooled flue, the law of conservation of energy is followed, and its expression is as follows:

[0116] Q i,n +Q A,a =Q el +Q pe +Q p (12)

[0117] In the formula, Q i,n is the kinetic energy of the incident particles, Q A,a is the surface energy of the particles, Q el and Q pe are the elastic energies stored in the elastic deformation zone and the plastic deformation zone respectively, and Q p is the energy loss when the particles undergo plastic deformation, and its expression is as follows:

[0118]

[0119] E s =19.167758 + 0.001000158T 2 -0.000017T 2 2 (20)

[0120] In the formula, u i,n is the incident normal velocity; m is the particle mass; F is the contact load; y is the elastic load limit; R is the particle radius; E * is the effective Young's modulus; v s and v p represent the Poisson's ratios of the flue wall and the particles respectively; E s and E prepresent the Young's moduli of the flue duct wall and the particles, respectively; T 1 and T 2 are the temperatures of the particles and the flue duct wall; Γ represents the adhesion work; its expression is as follows:

[0121]

[0122] In the formula, γ 1 and γ 2 are the free energies of the particles and the flue duct wall, respectively.

[0123] When the velocity of the particle hitting the water-cooled flue duct wall is zero, the kinetic energy is zero. The contact load F is solved according to Eqs. (12) - (21).

[0124] When the particle hits the flue duct wall, if the normal velocity of the particle is less than the critical elastic velocity, the particle undergoes plastic deformation; otherwise, the particle undergoes elastic deformation. The expression of the critical elastic velocity is as follows:

[0125]

[0126] In the formula, ρ is the particle density; C m is the proportionality coefficient.

[0127] When the particle collides and undergoes elastic deformation, Q pe and Q p are zero. The expression of the particle restitution coefficient is as follows:

[0128]

[0129] When the particle rebounds, the stored elastic energy is converted into the kinetic energy of the particle, and the particle begins to move away from the flue duct wall. The rebound velocity of the particle is:

[0130]

[0131] When the particle collides and undergoes plastic deformation, the expression of the particle restitution coefficient is as follows:

[0132]

[0133] When the particle rebounds, the stored elastic energy and plastic energy are converted into the kinetic energy of the particle. The rebound velocity of the particle is:

[0134]

[0135] When the incident angle of the particle is greater than the critical angle, the particle does not deposit. The expression of the critical angle is as follows:

[0136]

[0137] In the formula, f * is the effective friction coefficient; β is the effective coefficient of the contact radius; νp is the particle Poisson's ratio.

[0138] In this technical solution, the UDF subroutine's DEFINF_DPM_EROSION macro is used to compile and remove the model. The removal rate of particles is proportional to the thickness of the particles and the wall shear stress, and inversely proportional to the deposition strength coefficient. The particle removal model introduces the wall shear stress and the particle deposition thickness to accurately simulate the particle removal behavior. The removal rate expression is as follows:

[0139]

[0140] In the formula, k is the removal constant; ψ is the deposition layer strength coefficient; x f and τ w are the thickness of particle deposition and the wall shear stress, and the expression is:

[0141]

[0142] In the formula, m f is the fouling mass per unit area; μ is the kinematic viscosity of the gas; u is the particle velocity.

[0143] The fouling mass is the deposition mass minus the removal mass, and the expression is:

[0144]

[0145] In the formula, m r,t is the removal mass starting from time t; is the newly added removal mass within the time step Δt. The above-mentioned method for analyzing particle deposition in the water-cooled flue of a submerged arc furnace based on Fluent-UDF uses the user-defined function (UDF) in Fluent to establish a particle deposition model. On the basis of the particle deposition model, comprehensively considering the influence of temperature in the water-cooled flue and gravity, Saffman force, drag force, inertial force, thermophoretic force, and Brownian force on particle deposition during the particle transport process, it can accurately simulate and calculate the particle deposition mass and accurately simulate the particle deposition situation in the water-cooled flue of the submerged arc furnace during the actual production process, providing data support for daily production and maintenance.

[0146] The above content is only the preferred embodiment of the present invention. For those of ordinary skill in the art, according to the idea of the present technical content, many changes can be made in the specific implementation manner and application scope. As long as these changes do not deviate from the concept of the present invention, they all belong to the protection scope of this patent.

Claims

1. A method for analyzing particle deposition in a water-cooled flue of a smelting furnace based on Fluent-UDF, characterized in that: The method comprises the following steps: Step 1: Establish the geometric model of the water-cooled flue of the submerged arc furnace, import the model into ICEM for structured mesh division, and import the mesh model into Fluent software for flow field analysis and calculation; Step 2: The particle transport, deposition, rebound and removal model in the water-cooled flue was compiled in combination with the user-defined function (UDF) and imported into the Fluent software; Step 3: Set up gravity, energy, turbulence and discrete phase models in sequence; Step 4: Set the inlet boundary condition to velocity inlet, the outlet boundary condition to free outlet, and the inlet and outlet discrete phase boundary conditions to escape; Step 5: The SIMPLE algorithm is used to process the coupling relationship between velocity and pressure. The continuity, momentum and energy equations all use the second-order upwind difference format.

2. According to claim 1, a method for analyzing particle deposition in a water-cooled flue of a Fluent-UDF ore-fired smelting furnace is characterized by: The particle deposition and rebound model described in step 2 takes into account the elastic and elastoplastic deformations that occur when particles collide, as well as the effects of the particle incident kinetic energy, surface energy, and adhesion energy on deposition.

3. The method for analyzing particle deposition in a water-cooled flue of a Fluent-UDF ore-fired smelting furnace according to claim 1 is characterized in that: The particle size in step three follows the Rosin-Rammler distribution, with a particle size range of 5 to 140 μm, ignoring the interaction between particles during transportation and the effect of particles on high-temperature furnace gas.

4. The method for analyzing particle deposition in a water-cooled flue of a Fluent-UDF ore-fired smelting furnace according to claim 1 is characterized in that: The particles carried in the high-temperature furnace gas flow in from the water-cooled flue furnace mouth section and flow out from the outlet section. The flow direction of the cooling water flows in from the water-cooled inlet and flows out from the outlet. The high-temperature furnace gas generated during the smelting process of the ore-fired furnace is transported through the water-cooled flue. During the transportation process, the furnace gas temperature will fluctuate within a certain range (800K to 1100K) under the influence of the cooling water. The temperature fluctuation will affect the physical parameters of the particles and the flue wall, and then affect the particle deposition. The particle deposition model considers the influence of the temperature in the water-cooled flue on the particle deposition. The particle deposition judgment condition is based on the particle recovery coefficient e 2 , incident angle θ and critical angle θ cr Joint decision; use the DEFINF_DPM_EROSION macro in the UDF subroutine to compile the particle deposition and rebound model; when the particle collides with the wall, if e 2 <0 and θ<θ cr , then the particles are deposited and stored in UDM; Otherwise the particle rebounds, and the rebound speed is calculated according to the energy conservation model.

5. The method for analyzing particle deposition in a water-cooled flue of a Fluent-UDF ore-fired smelting furnace according to claim 1 is characterized in that: Based on the particle size and temperature distribution characteristics in the flue, the force analysis during particle transportation mainly considers gravity, Saffman force, thermophoretic force, drag force, inertial force and Brownian force. The DEFINE_DPM_DRAG macro is used to expand the drag force calculation to accurately simulate the interaction force generated when the furnace gas and particles move relative to each other. The Lagrangian method and particle force balance analysis are combined to predict the movement trajectory of the particles. The control equation of the particle trajectory is: The right side of formula (1) is drag force, gravity and inertia force, Saffman force, thermophoresis force and Brownian force, u p The velocity of the particles; u1 is the flow rate of the furnace gas; ρ p Particle density; ρ furnace gas density; m p The mass of the particle; τ r The relaxation time of a particle is expressed as follows: In the formula, C D is the drag coefficient; μ is the dynamic viscosity of the furnace gas; Re is the particle Reynolds number, Re = ρd p |u p -u1| / μ; When Re<0.01, C D It is expressed as: When 0.01≤Re<20, C D It is expressed as: When Re>20, C D It is expressed as: Saffman Force F saff The expression is as follows: In the formula, K C =2.594,d ij is the deformation tensor; The thermophoretic force is expressed as follows: Where, μ is the gas dynamic viscosity; C s is a constant, C s =1.17; C t is a constant, C t =2.18; C m is a constant, C m =1.14; m p is the particle mass; T is the fluid temperature; k p is the thermal conductivity of the particles; k is the thermal conductivity of the gas based on the gas translational kinetic energy, expressed as: k n The expression for the Knudsen number is: Where λ is the average free path of gas molecules; d p is the particle radius; The Brownian force expression is: Where ξ is a Gaussian random number with a mean of 0 and a variance of 1; Δt is the time step used in the calculation; S0 is the spectral intensity; T is the absolute temperature of the fluid; v is the kinematic viscosity of the air; k b is the Boltzmann constant; C c is a correction to Stokes' drag law.

6. The method for analyzing particle deposition in a water-cooled flue of a Fluent-UDF ore-fired smelting furnace according to claim 1, characterized in that: The method follows the energy conservation when the particles collide with the flue wall, and its expression is as follows: Q i,n +Q A,a =Q el +Q pe +Q p (12) In the formula, Q i,n is the kinetic energy of the incident particle, Q A,a is the surface energy of the particle, Q el and Q pe is the elastic energy stored in the elastic deformation zone and the plastic deformation zone, Q p is the energy loss when the particle undergoes plastic deformation, and the kinetic energy expression is as follows: E s =19.167758+0.001000158T2-0.000017T2 2 (20) In the formula, u i,n is the incident normal velocity; m is the particle mass; F is the contact load; y is the elastic load limit; R is the particle radius; E * is the effective Young's modulus; v s and v p are the Poisson's ratios of the flue wall and particles respectively; E s and E p represents the Young's modulus of the flue wall and the particle, respectively; T1 and T2 are the particle and flue wall temperatures; Γ represents the adhesion work; Its expression is as follows: Where γ1 and γ2 are the free energies of particles and flue wall, respectively. When the velocity of the particles hitting the water-cooled flue wall is zero, the kinetic energy is zero; the contact load F is solved according to equations (12) to (21).

7. The method for analyzing particle deposition in a water-cooled flue of a Fluent-UDF ore-fired smelting furnace according to claim 1, characterized in that: When the particles hit the wall of the water-cooled flue, the normal velocity of the particles is less than the critical elastic velocity, and the particles undergo plastic deformation; otherwise, the particles undergo elastic deformation. The critical elastic velocity expression is as follows: Where ρ is the particle density; c is the proportionality coefficient; When particles collide, elastic deformation Q occurs pe and Q p is zero, and the particle recovery coefficient expression is as follows: When the particles rebound, the stored elastic energy is converted into particle kinetic energy, and the particles begin to move away from the flue wall; the particle rebound speed is: When particles collide, elastic-plastic deformation occurs, and the particle recovery coefficient expression is as follows: When the particles rebound, the stored elastic energy and plastic energy are converted into particle kinetic energy, and the particle rebound speed is:

8. The method for analyzing particle deposition in a water-cooled flue of a Fluent-UDF ore-fired smelting furnace according to claim 1, characterized in that: When the particle incident angle is greater than the critical angle, the particles do not settle. The critical angle expression is as follows: In the formula, f * is the effective friction coefficient; β is the effective coefficient of contact radius; ν p is the particle Poisson's ratio.

9. The method for analyzing particle deposition in a water-cooled flue of a Fluent-UDF ore-fired smelting furnace according to claim 1, characterized in that: The method uses the DEFINF_DPM_EROSION macro in the UDF subroutine to compile the removal model described in step 2. The particle removal rate is proportional to the particle deposition thickness and the wall shear stress, and inversely proportional to the deposition intensity coefficient. The particle removal model introduces the wall shear stress and the particle deposition thickness to accurately simulate the particle removal behavior. The removal rate expression is as follows: Where k is the removal constant; ψ is the strength coefficient of the sediment layer; x f and τ w is the thickness of particle deposition and the wall shear stress, and the expression is: In the formula, m f is the fouling mass per unit area; μ is the kinematic viscosity of the gas; u is the particle velocity.

10. The method for analyzing particle deposition in a water-cooled flue of a Fluent-UDF ore-fired smelting furnace according to claim 1, characterized in that: The method uses the deposited mass minus the removed mass to obtain the dirt mass, which can be expressed as: In the formula, m r,t is the mass removed starting from time t; is the additional mass removed within the time step Δt.

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