A comprehensive evaluation method for coal gun-hot air pipe arrangement of lead-zinc smelting closed blast furnace

Abstract

The present application relates to a kind of lead-zinc smelting closed blast furnace coal gun-hot blast pipe arrangement mode comprehensive evaluation method, according to coal gun-hot blast pipe arrangement form parameter to determine the coal gun arrangement type to be evaluated;Numerical simulation of coal injection combustion process of coal gun-hot blast pipe is established;According to the distribution of multiple physical fields under different working conditions and the combustion of coal powder movement, extract analysis evaluation index;Quantitative evaluation of coal gun arrangement mode and blast parameters;The method of the present application combines the characteristics of coal injection combustion process and computer numerical simulation, which can realize the system evaluation of closed blast furnace (ISF) coal gun arrangement mode, help to strengthen the understanding of closed blast furnace coal injection process, provide guidance for the optimization of coal injection combustion process in the field, and provide protection for the smooth operation of lead-zinc smelting ISF.

Description

Technical Field

[0001] This invention relates to the field of quantitative evaluation of coal lance-hot duct layout, specifically to a comprehensive evaluation method for the coal lance-hot duct layout of a closed blast furnace in lead-zinc smelting. Background Technology

[0002] The coal lance is a key piece of equipment in the lead-zinc smelting process using a closed blast furnace. Pulverized coal from the coal bunker enters the furnace through the coal conveying pipe and then through the coal lance that extends into the duct. The pulverized coal mixes with the hot air in the duct and is heated. The pulverized coal then burns and enters the lower vortex zone of the closed blast furnace to continue burning, providing reducing gases and heat for the reduction of the ore inside the closed blast furnace.

[0003] In recent years, with the development of closed blast furnaces in lead-zinc smelting, higher demands have been placed on their economic efficiency. Pulverized coal injection in closed blast furnaces for lead-zinc smelting has received close attention in terms of reducing production costs. The movement and combustion behavior of pulverized coal after entering the duct are significantly affected by the arrangement of the coal lances and the hot air parameters. An inappropriate coal lance-hot air duct arrangement not only results in insufficient heating of the pulverized coal within the duct, affecting the subsequent combustion process and gas flow distribution, but also reduces the utilization of pulverized coal combustion, posing a potential safety hazard to the closed blast furnaces in lead-zinc smelting.

[0004] In existing technologies, coal pulverized coal combustion evaluation indicators mainly focus on the arrangement of the coal lances, with particular emphasis on the burnout rate and diffusion angle of coal pulverized coal in a single lance. Both indicators reflect the overall combustion and diffusion of coal pulverized coal within the duct. However, coal pulverized coal has a wide particle size distribution, and the movement and combustion of particles of different sizes vary. In particular, after coal pulverized coal is ejected from the hot air duct and enters the swirling zone inside the furnace, the trajectories and pyrolysis states of coal pulverized coal particles of different sizes vary. The above two indicators cannot reflect the differences in diffusion between different particles. Furthermore, existing evaluation methods fail to consider the coordinated arrangement between the coal lances and the hot air duct. In actual lead-zinc closed blast furnace production, the angle of the duct directly affects the velocity vector direction of the hot air and the subsequent formation of the swirling zone inside the furnace.

[0005] Therefore, based on the characteristics of the actual pulverized coal injection process, this paper comprehensively considers the impact of the diffusion of pulverized coal particles of different sizes on the combustion and utilization of pulverized coal, and provides a comprehensive evaluation method for the arrangement of pulverized coal guns and hot air pipes in a closed blast furnace for lead-zinc smelting, based on the arrangement of pulverized coal guns and hot air pipes. Summary of the Invention

[0006] In order to overcome the above-mentioned defects in the prior art, this invention starts from the characteristics of the actual pulverized coal injection process, comprehensively considers the influence of the diffusion of pulverized coal particles of different sizes on the combustion and utilization of pulverized coal, and provides a comprehensive evaluation method for the arrangement of pulverized coal guns and hot air pipes in a closed blast furnace for lead-zinc smelting based on the arrangement of pulverized coal guns and hot air pipes.

[0007] This invention provides a comprehensive evaluation method for the coal lance-hot blast pipe arrangement of a closed blast furnace in lead-zinc smelting.

[0008] S1. Determine the coal gun arrangement type to be evaluated based on the coal gun-hot air duct layout parameters;

[0009] S2. Establish a numerical simulation of the coal injection and combustion process of the coal gun-hot air pipe;

[0010] S3. Extract and analyze evaluation indicators based on the multi-physics field distribution and pulverized coal movement and combustion under different working conditions;

[0011] S4. The evaluation method is as follows: the coal gun-hot air pipe arrangement is evaluated based on two major indicators: the coal powder burnout rate and the degree of stratified diffusion. The higher the coal powder burnout rate and the higher the degree of stratified diffusion, the more reasonable the coal gun-hot air pipe arrangement is.

[0012] In S1, the arrangement parameters include at least: the diameter of the coal gun, the insertion position of the coal gun in the hot air duct, the angle between the center line of the coal gun and the center line of the air duct, and the horizontal distance from the end of the coal gun outlet to the outlet of the hot air duct.

[0013] The numerical simulation of the coal injection combustion process in S2, which involves establishing a physical model of the coal gun-hot air pipe, a mathematical model of pulverized coal combustion and gas-particle two-phase flow, and determining the corresponding boundary conditions, is as follows.

[0014] In S2, a numerical simulation physical model and boundary conditions are established based on the blast and pulverized coal injection conditions, pulverized coal properties, pulverized coal gun and duct size, and pulverized coal gun arrangement in the lower part of the lead-zinc sealed blast furnace. The mathematical model is determined by combining the principles of airflow, pulverized coal motion and combustion, and interphase interaction. Multi-level and multi-factor numerical simulation calculations are performed on the parameters of different pulverized coal gun-hot duct arrangement methods to obtain the multi-physical field distribution of pulverized coal particles in the pulverized coal gun-duct with different parameters and the pulverized coal motion and combustion.

[0015] In S3, the evaluation indicators include pulverized coal combustion and utilization indicators and pulverized coal particle diffusion indicators.

[0016] Coal powder combustion utilization indicators include the burnout rate of the combustible portion of coal powder, and coal powder particle diffusion indicators include the diffusion uniformity of coal powder particles and the distribution of coal powder particles of different sizes.

[0017] The comparative analysis and evaluation method for pulverized coal combustion utilization index and particle diffusion index is as follows: the greater the burnout rate of the combustible part of pulverized coal, the better the pulverized coal combustion utilization index; the greater the pulverized coal particle diffusion index, the better the diffusion situation.

[0018] The technical solution of this invention has the following advantages:

[0019] The method described in this invention, combining the characteristics of the pulverized coal combustion process with computer numerical simulation, can achieve a systematic evaluation of the coal gun arrangement of the closed blast furnace (ISF), which helps to enhance the understanding of the pulverized coal injection process in the closed blast furnace, provides guidance for the optimization of the on-site pulverized coal combustion process, and ensures the smooth operation of lead-zinc smelting in the ISF. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 A schematic diagram of the comprehensive evaluation method described in this invention;

[0022] Figure 2 A schematic diagram of the coal gun arrangement described in Embodiment 2 of the present invention;

[0023] Figure 3 A schematic diagram of the boundary condition types for numerical simulation research as described in Embodiment 2 of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] Example 1: As Figure 1 As shown in the figure, this embodiment provides a comprehensive evaluation method for the coal gun-hot air pipe arrangement of a closed blast furnace in lead-zinc smelting.

[0027] S1. Determine the coal gun arrangement type to be evaluated based on the coal gun-hot air duct layout parameters;

[0028] In S1, the arrangement parameters include at least: the diameter of the coal gun, the insertion position of the coal gun in the hot air duct, the angle between the center line of the coal gun and the center line of the air duct, and the horizontal distance from the end of the coal gun outlet to the outlet of the hot air duct.

[0029] S2. Establish a numerical simulation of the coal injection and combustion process of the coal gun-hot air pipe;

[0030] The numerical simulation of the coal injection combustion process in S2, which involves establishing a physical model of the coal gun-hot air pipe, a mathematical model of pulverized coal combustion and gas-particle two-phase flow, and determining the corresponding boundary conditions, is as follows.

[0031] In S2, a numerical simulation physical model and boundary conditions are established based on the blast and pulverized coal injection conditions, pulverized coal properties, pulverized coal gun and duct size, and pulverized coal gun arrangement in the lower part of the lead-zinc sealed blast furnace. The mathematical model is determined by combining the principles of airflow, pulverized coal motion and combustion, and interphase interaction. Multi-level and multi-factor numerical simulation calculations are performed on the parameters of different pulverized coal gun-hot duct arrangement methods to obtain the multi-physical field distribution of pulverized coal particles in the pulverized coal gun-duct with different parameters and the pulverized coal motion and combustion.

[0032] S3. Based on the multi-physics field distribution and pulverized coal movement and combustion under different operating conditions, extract and analyze evaluation indicators. In S3, the evaluation indicators include pulverized coal combustion utilization indicators and pulverized coal particle diffusion indicators.

[0033] Among them, the coal powder combustion utilization index includes the burnout rate of the combustible part of the coal powder, and the coal powder particle diffusion index includes the diffusion uniformity of coal powder particles and the distribution of coal powder particles of different sizes.

[0034] The comparative analysis and evaluation method for pulverized coal combustion utilization index and particle diffusion index is as follows: the greater the burnout rate of the combustible part of pulverized coal, the better the pulverized coal combustion utilization index; the greater the pulverized coal particle diffusion index, the better the diffusion situation.

[0035] Specifically, the percentage of pulverized coal burned out, that is, the combustion rate of the combustible portion of pulverized coal, can be expressed as:

[0036] ,

[0037] in, This refers to the ash content in the original pulverized coal. This represents the ash content of pulverized coal at a specific location during the combustion process.

[0038] The particle diffusion of pulverized coal at the hot air duct outlet, i.e., the degree of stratified diffusion, is divided into the uniformity of pulverized coal particle diffusion and the distribution of pulverized coal particles of different sizes, which can be expressed as:

[0039] ,

[0040] Among them, γ is the stratified diffusion degree index, and the larger the index, the better the coal powder diffusion; The index is the uniformity of coal powder concentration in the cross section. The larger the index, the more uniform the coal powder and hot air are mixed, the greater the heat exchange intensity between each coal powder particle and the surrounding hot air, and the easier it is for oxygen in the hot air to diffuse to the particle surface, thereby promoting the combustion and utilization of individual coal powder particles. For this section, the first Coal powder concentration in each grid; This is the area-weighted average of the coal powder concentration at that cross section. For this section, the first The area of ​​each grid; This is a particle stratification index. The larger the index, the weaker the particle stratification phenomenon and the more uniform the mixing of particles of different sizes. The number of particle size categories. This indicates the height of the center of gravity of a particle of a certain size in the vertical direction. It is the overall center of gravity height of particles of all sizes.

[0041] S4. Quantitative evaluation of the coal gun-hot air pipe layout: The evaluation method is to evaluate the coal gun-hot air pipe layout based on two major indicators: coal powder burnout rate and stratified diffusion degree. Among them, the higher the coal powder burnout rate and the higher the stratified diffusion degree, the more reasonable the coal gun-hot air pipe layout is considered.

[0042] Furthermore, based on the numerical simulation and the extraction and analysis of evaluation indicators, the coal gun-hot air pipe layout methods under various types and parameter levels are evaluated and analyzed. Based on the evaluation indicators, the optimal layout method is determined within the experimental range.

[0043] In this embodiment, the comprehensive evaluation method takes into account the influence of the stratification phenomenon of different particle sizes in the coal powder diffusion behavior on the coal powder combustion rate, provides a systematic evaluation scheme for the coal gun-hot air pipe layout, and also provides support for the design and optimization of the coal gun-hot air pipe layout.

[0044] The method described in this embodiment combines computer numerical simulation technology. First, it determines the parameters of the coal gun-hot air duct arrangement, clarifies the blower parameters and pulverized coal injection parameters, and combines the interaction mechanism between pulverized coal and hot air. Through numerical simulation of the movement and combustion process of pulverized coal in the coal gun and subsequent air duct branches and air outlet sleeves, it starts from the macroscopic and microscopic heat and mass transfer processes, with the goal of energy saving, emission reduction and saving equipment operation and maintenance costs. It establishes evaluation indicators for the movement and combustion behavior of pulverized coal, completes the systematic evaluation of the ISF pulverized coal injection and blower combined injection mode, and constructs a comprehensive quantitative evaluation method for the injection mode.

[0045] This method, combining the characteristics of pulverized coal combustion process with computer numerical simulation, can achieve a systematic evaluation of the coal gun arrangement of the closed blast furnace (ISF). It helps to enhance the understanding of the pulverized coal injection process in the closed blast furnace, provides guidance for the optimization of the on-site pulverized coal combustion process, and ensures the smooth operation of lead-zinc smelting in the ISF.

[0046] Example 2: Based on Example 1, this example is illustrated with a specific instance.

[0047] like Figure 2 As shown in the figure, a typical single coal lance arrangement is presented for a lead-zinc sealed blast furnace. The parameters determining the coal lance arrangement are: the horizontal distance from the end of the coal lance outlet to the outlet of the hot air pipe; the inner diameter of the coal lance; the angle between the coal lance and the hot air pipe; and the insertion position of the coal lance into the hot air pipe.

[0048] Based on actual production conditions, the coal gun-hot air pipe arrangement for the example benchmark is set as follows: the coal gun is inserted at the bottom; the horizontal distance L between the coal gun outlet and the hot air pipe outlet is 100mm; the inner diameter of the coal gun is 12mm; the angle between the hot air pipe and the horizontal line is 12°, and the angle between the coal gun and the hot air pipe is 3°.

[0049] Numerical simulation calculations are performed using the coal gun arrangement under a specific working condition as an example. Figure 3 As shown, it is the physical model for numerical simulation. The mathematical model for the two-phase reaction flow of hot air and pulverized coal in the coal gun-duct is shown in Table 1-2. The pulverized coal combustion process includes three stages: moisture evaporation, thermal desorption of volatiles and their combustion, and residual carbon combustion. The mathematical models for each stage are, in order, a diffusion control model, a finite rate / vortex dissipation model, and a dynamic / diffusion model.

[0050] Table 1 Numerical Simulation Model of Gas Phase Flow Heat Transfer

[0051]

[0052] Table 2 Numerical simulation model of heat transfer during particle motion

[0053]

[0054] in, , Fluid and particle densities, respectively, in kg / m³ 3 ; , These are the fluid velocity vectors, in m / s; The average pressure of the fluid, in Pa; , These are the molecular dynamic viscosity and turbulent viscosity of the fluid, respectively. ; For time, s; for Gravitational acceleration in the direction of gravity, m / s 2 ; The mass of the particles is in kg. denoted as the particle mass change rate, in kg / s. Where Re is the traction coefficient, Re is the Reynolds number, and Pr is the Prandtl number; , These are the gas phase and particle temperatures, respectively, in K; It is the heat of reaction; For particle specific heat, ; For particle area, m 2 ; The emissivity of the particle; is the Stefan-Boltzmann constant.

[0055] The boundary conditions of the numerical simulation model are as follows. The types of boundary conditions in the numerical simulation are as follows: Figure 3 As shown.

[0056] Table 3 Boundary conditions for numerical simulation of pulverized coal combustion

[0057]

[0058] Furthermore, the coal gun-hot air pipe arrangement parameters are as follows: coal gun diameter 20mm; coal gun outlet distance to hot air pipe outlet 310mm; coal gun angle 7°, i.e., 5° angle with hot air pipe; coal gun bottom insertion. The coal powder burnout rate and coal powder stratification diffusion degree under the baseline working condition and this working condition are shown in Table 4.

[0059] Table 4 Evaluation Indicators for Different Working Conditions

[0060]

[0061] According to the results in Table 4, compared with the baseline condition, when the coal gun-hot air pipe arrangement parameters are: coal gun diameter 20mm; coal gun outlet distance from hot air pipe outlet 310mm; coal gun angle 7 degrees, i.e., 5° angle with hot air pipe; and the bottom of the coal gun is inserted, the coal powder stratification diffusion degree and combustion rate evaluation index are greater, the coal powder and hot air are mixed more fully, and the pyrolysis state of the coal powder is better. Under these conditions, the coal gun-hot air pipe arrangement is superior.

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A comprehensive evaluation method for the coal lance-hot blast pipe arrangement of a closed blast furnace in lead-zinc smelting, characterized in that, S1. Determine the coal gun arrangement type to be evaluated based on the coal gun-hot air duct layout parameters; S2. Establish a numerical simulation of the coal injection and combustion process of the coal gun-hot air pipe; S3. Extract and analyze evaluation indicators based on the multi-physics field distribution and pulverized coal movement and combustion under different working conditions; S4. Quantitative evaluation of the coal gun-hot air pipe layout method: The evaluation method is to evaluate the coal gun-hot air pipe layout method based on two major indicators: coal powder burnout rate and stratified diffusion degree; the higher the coal powder burnout rate and the higher the stratified diffusion degree, the more reasonable the coal gun-hot air pipe layout method is. In S3, the evaluation indicators include pulverized coal combustion utilization indicators and pulverized coal particle diffusion indicators. The pulverized coal combustion utilization indicators include the burnout rate of the combustible portion of pulverized coal, and the pulverized coal particle diffusion indicators include the diffusion uniformity of pulverized coal particles and the distribution of pulverized coal particles of different sizes. The comparative analysis and evaluation method for pulverized coal combustion utilization indicators and particle diffusion indicators is as follows: the higher the burnout rate of the combustible portion of pulverized coal, the better the pulverized coal combustion utilization indicators; the greater the degree of stratified diffusion of pulverized coal, the better the diffusion situation. Specifically, the percentage of pulverized coal burned out, that is, the burn rate of the combustible portion of pulverized coal, is expressed as: （1）， in, This refers to the ash content in the original pulverized coal. This represents the ash content of pulverized coal at a specific location during the combustion process. The particle diffusion of pulverized coal at the hot air duct outlet, i.e., the degree of stratified diffusion, is divided into the uniformity of pulverized coal particle diffusion and the distribution of pulverized coal particles of different sizes, expressed as: ， in, This is an indicator of the degree of stratified diffusion; the higher the index, the better the coal powder diffusion. The index is the uniformity of coal powder concentration in the cross section. The larger the index, the more uniform the coal powder and hot air are mixed, the greater the heat exchange intensity between each coal powder particle and the surrounding hot air, and the easier it is for oxygen in the hot air to diffuse to the particle surface, thereby promoting the combustion and utilization of individual coal powder particles. For this section, the first The coal powder concentration in each grid; This is the area-weighted average of the coal powder concentration at that cross section. For this section, the first The area of ​​each grid; This is a particle stratification index. The larger the index, the weaker the particle stratification phenomenon and the more uniform the mixing of particles of different sizes. The number of particle size categories. This indicates the height of the center of gravity of a particle of a certain size in the vertical direction. It is the overall center of gravity height of particles of all sizes.

2. The comprehensive evaluation method for the coal lance-hot blast pipe arrangement of a closed blast furnace for lead-zinc smelting according to claim 1, characterized in that, In S1, the arrangement parameters include at least: the diameter of the coal gun, the insertion position of the coal gun in the hot air duct, the angle between the center line of the coal gun and the center line of the air duct, and the horizontal distance from the end of the coal gun outlet to the outlet of the hot air duct.

3. The comprehensive evaluation method for the coal lance-hot blast pipe arrangement of a closed blast furnace for lead-zinc smelting according to claim 1, characterized in that, The numerical simulation of the coal injection combustion process in S2, which involves establishing a physical model of the coal gun-hot air pipe, a mathematical model of pulverized coal combustion and gas-particle two-phase flow, and determining the corresponding boundary conditions, is as follows.

4. The comprehensive evaluation method for the coal lance-hot blast pipe arrangement of a closed blast furnace for lead-zinc smelting according to claim 3, characterized in that, In S2, a numerical simulation physical model and boundary conditions are established based on the blast and pulverized coal injection conditions, pulverized coal properties, pulverized coal gun and duct size, and pulverized coal gun arrangement in the lower part of the lead-zinc sealed blast furnace. The mathematical model is determined by combining the principles of airflow, pulverized coal motion and combustion, and interphase interaction. Multi-level and multi-factor numerical simulation calculations are performed on the parameters of different pulverized coal gun-hot duct arrangement methods to obtain the multi-physical field distribution of pulverized coal particles in the pulverized coal gun-duct with different parameters and the pulverized coal motion and combustion.

Images