Comprehensive evaluation method for coal lance-hot air pipe arrangement mode of lead-zinc smelting closed blast furnace

Abstract

The invention relates to a comprehensive evaluation method for a coal gun-hot air pipe arrangement mode of a lead-zinc smelting closed blast furnace. The arrangement type of a coal gun to be evaluated is determined according to parameters of the coal gun-hot air pipe arrangement mode; establishing numerical simulation of the coal injection combustion process of the coal gun-hot air pipe; according to multi-physical field distribution and pulverized coal movement combustion conditions under different working conditions, analysis and evaluation indexes are extracted; performing quantitative evaluation on a coal gun arrangement mode and blast parameters; according to the method, the coal injection combustion process characteristics and computer numerical simulation are combined, systematic evaluation of the coal lance arrangement mode of the ISF can be achieved, understanding of the coal injection process of the ISF can be enhanced, guidance is provided for optimization of the on-site coal injection combustion process, and guarantee is provided for smooth lead and zinc smelting of the ISF.

Description

Technical Field

[0001] The invention relates to the technical field of quantitative evaluation of coal gun-hot blast pipe arrangement modes, and in particular to a comprehensive evaluation method for coal gun-hot blast pipe arrangement modes of a lead-zinc smelting closed blast furnace. Background Art

[0002] The coal gun is a key equipment in the pulverized coal injection technology in the lead-zinc smelting process using a closed blast furnace for lead-zinc smelting. The pulverized coal from the coal bunker passes through the coal conveying pipeline and enters the furnace through the coal gun extended into the air duct; the pulverized coal is mixed with the hot air in the air duct and heated, and then the pulverized coal burns and enters the lower cyclone area of ​​the closed blast furnace for lead-zinc smelting to continue burning, providing reducing gas and heat for the reduction of ore inside the closed blast furnace for lead-zinc smelting.

[0003] In recent years, with the development of closed blast furnaces for lead and zinc smelting, higher requirements have been put forward for the economic benefits of closed blast furnaces for lead and zinc smelting. Pulverized coal injection in closed blast furnaces for lead and zinc smelting has received close attention in reducing production costs. The movement and combustion behavior of pulverized coal after entering the air duct are greatly affected by the arrangement of coal guns and hot air parameters. Inappropriate arrangement of coal guns and hot air ducts will not only cause insufficient heating of pulverized coal in the air duct, thus affecting the subsequent combustion process and gas flow distribution, but also reduce the utilization of pulverized coal combustion, bringing hidden dangers to the safe production of closed blast furnaces for lead and zinc smelting.

[0004] In the prior art, the coal powder combustion evaluation index is mainly concentrated on the arrangement of the coal gun, and the focus is on the burnout rate and diffusion angle of the coal powder of a single coal gun. Both indicators reflect the overall combustion and diffusion of the coal powder in the air duct. However, the particle size distribution range of the coal powder particles is large, and the movement and combustion conditions of particles of different particle sizes are different. In particular, after the coal powder is ejected from the hot air duct and enters the vortex zone in the furnace, the movement trajectories and pyrolysis states of coal powder particles of different particle sizes are different. The above two indicators cannot reflect the differences in diffusion conditions between different particles. In addition, the existing evaluation method fails to take into account the coordinated arrangement between the coal gun and the hot air duct. In the actual production of lead-zinc closed blast furnaces, the angle of the air duct will directly affect the velocity vector direction of the hot air and the subsequent formation of the vortex zone in the furnace.

[0005] Therefore, starting from the actual characteristics of coal injection process, the influence of the diffusion of coal powder with different particle sizes on the combustion and utilization of coal powder is comprehensively considered, and based on the coordinated arrangement of coal gun and hot air pipe, a comprehensive evaluation method of coal gun and hot air pipe arrangement for closed blast furnace of lead and zinc smelting is provided. Summary of the invention

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

[0007] The present invention provides a comprehensive evaluation method for the arrangement of coal guns and hot air pipes in a closed blast furnace for lead and zinc smelting. S1. Determine the type of coal gun arrangement to be evaluated according to the coal gun-hot air pipe arrangement form parameters; S2. Establishing numerical simulation of coal injection combustion process of coal gun-hot air pipe; S3. Extract, analyze and evaluate indicators based on the distribution of multiple physical fields and the movement and combustion of pulverized coal under different working conditions; S4. The evaluation method is: evaluate the coal gun-hot air pipe arrangement mode according to the two major indicators of coal powder burnout rate and stratification diffusion degree; the greater the coal powder burnout rate and the greater the stratification diffusion degree, the more reasonable the coal gun-hot air pipe arrangement mode is.

[0008] In S1, the layout parameters include at least: the diameter of the coal gun, the insertion position of the coal gun in the hot air pipe, the angle between the center line of the coal gun and the center line of the air pipe, and the horizontal distance between the end of the coal gun outlet and the hot air pipe outlet.

[0009] The numerical simulation of the coal injection combustion process of the coal gun-hot air duct in S2 includes establishing the physical model of the coal gun-hot air duct, the mathematical model of coal powder combustion and gas-particle two-phase flow, and determining the corresponding fixed solution conditions.

[0010] In S2, a numerical simulation physical model and solution conditions are established according to the blast and coal injection conditions, coal powder properties, coal gun and air duct sizes, and coal gun arrangement of the lower part of the lead-zinc closed blast furnace. The mathematical model is determined by combining the principles of air flow, coal powder movement and combustion, and phase interaction. Multi-level and multi-factor numerical simulation calculations are performed on the parameters of different coal gun-hot air duct arrangements to obtain the multi-physical field distribution of coal powder particles in coal guns and air ducts with different parameters and the coal powder movement and combustion conditions.

[0011] In S3, the evaluation indexes include the pulverized coal combustion utilization index and the pulverized coal particle diffusion index.

[0012] 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 the coal powder particles and the distribution of coal powder particles of different particle sizes.

[0013] The comparative analysis and evaluation method of coal powder combustion utilization index and particle diffusion index is as follows: the greater the burnout rate of the combustible part of the coal powder, the better the coal powder combustion utilization index; the greater the coal powder particle diffusion index, the better the diffusion situation.

[0014] The technical solution of the present invention has the following advantages: The method described in the present invention combines the characteristics of the coal injection combustion process and computer numerical simulation to achieve a systematic evaluation of the coal gun arrangement mode of the closed blast furnace (ISF), which helps to enhance the understanding of the coal injection process of the closed blast furnace, provide guidance for the optimization of the on-site coal injection combustion process, and provide a guarantee for the smooth progress of lead and zinc smelting in the ISF. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 Schematic diagram of the comprehensive evaluation method of the present invention; Figure 2 A schematic diagram of the arrangement of the coal guns according to Embodiment 2 of the present invention; Figure 3 Schematic diagram of boundary condition types for numerical simulation research described in Example 2 of the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In addition, 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.

[0019] Example 1: Figure 1 As shown, this embodiment provides a comprehensive evaluation method for the arrangement of coal guns and hot air pipes in a closed blast furnace for lead and zinc smelting. S1. Determine the type of coal gun arrangement to be evaluated according to the coal gun-hot air pipe arrangement form parameters; In S1, the layout parameters include at least: the diameter of the coal gun, the insertion position of the coal gun in the hot air pipe, the angle between the center line of the coal gun and the center line of the air pipe, and the horizontal distance between the end of the coal gun outlet and the hot air pipe outlet.

[0020] S2. Establishing numerical simulation of coal injection combustion process of coal gun-hot air pipe; The numerical simulation of the coal injection combustion process of the coal gun-hot air duct in S2 includes establishing the physical model of the coal gun-hot air duct, the mathematical model of coal powder combustion and gas-particle two-phase flow, and determining the corresponding fixed solution conditions.

[0021] In S2, a numerical simulation physical model and solution conditions are established according to the blast and coal injection conditions, coal powder properties, coal gun and air duct sizes, and coal gun arrangement of the lower part of the lead-zinc closed blast furnace. The mathematical model is determined by combining the principles of air flow, coal powder movement and combustion, and phase interaction. Multi-level and multi-factor numerical simulation calculations are performed on the parameters of different coal gun-hot air duct arrangements to obtain the multi-physical field distribution of coal powder particles in coal guns and air ducts with different parameters and the coal powder movement and combustion conditions.

[0022] S3. Extract, analyze and evaluate indicators based on the distribution of multiple physical fields and the movement and combustion of pulverized coal under different working conditions. In S3, the evaluation indicators include pulverized coal combustion utilization indicators and pulverized coal particle diffusion indicators.

[0023] 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 the coal powder particles and the distribution of coal powder particles with different particle sizes.

[0024] The comparative analysis and evaluation method of coal powder combustion utilization index and particle diffusion index is as follows: the greater the burnout rate of the combustible part of the coal powder, the better the coal powder combustion utilization index; the greater the coal powder particle diffusion index, the better the diffusion situation.

[0025] Specifically, the coal powder burnout percentage, that is, the burnout rate of the combustible part of the coal powder, can be expressed as: , in, is the ash content in the original coal powder; It is the ash content of coal powder at a certain position in the combustion process.

[0026] The particle diffusion of pulverized coal at the outlet of the hot air pipe, that is, the degree of stratified diffusion, is divided into the diffusion uniformity of pulverized coal particles and the distribution of pulverized coal particles with different particle sizes, which can be expressed as: , Among them, γ is the index of stratified diffusion degree, and the larger the index is, the better the coal powder diffusion is; It is the index of uniformity of cross-section coal powder concentration. The larger the index is, the more uniform the mixing of coal powder and hot air is, the greater the intensity of heat exchange between each coal powder particle and the surrounding hot air is, and the oxygen in the hot air is easy to diffuse to the particle surface, thereby promoting the combustion and utilization of individual coal powder particles; For this section The coal powder concentration of each grid; is the area-weighted average of the coal powder concentration in the cross section; For this section The area of ​​the grid; It is an index of particle stratification. The larger the index is, the weaker the particle stratification phenomenon is, and the particles of different particle sizes are mixed more evenly. is the number of particle size types, Indicates the height of the center of gravity of a particle of a certain size in the vertical direction; is the overall center of gravity height of particles of all particle sizes.

[0027] S4. Quantitative evaluation of the coal gun-hot air duct arrangement method. The evaluation method is to evaluate the coal gun-hot air duct arrangement method based on two major indicators: coal powder burnout rate and stratification diffusion degree. Among them, the greater the coal powder burnout rate and the greater the stratification diffusion degree, the more reasonable the coal gun-hot air duct arrangement method is.

[0028] Furthermore, according to the numerical simulation and the extraction and analysis process of the evaluation indexes, the coal gun-hot air duct arrangement methods under various types and parameter levels are evaluated and analyzed, and the optimal arrangement method is determined within the experimental range according to the evaluation indexes.

[0029] In this embodiment, the comprehensive evaluation method comprehensively considers the influence of the stratification phenomenon of particles of different particle sizes in the diffusion behavior of coal powder on the burnout rate of coal powder, provides a systematic evaluation scheme for the coal gun-hot air pipe arrangement, and also provides support for the design and optimization of the coal gun-hot air pipe arrangement.

[0030] That is, the method of this embodiment is combined with computer numerical simulation technology, firstly, the parameters of the coal gun-hot air duct arrangement are determined, the blast parameters and the coal powder blowing parameters are clarified, and the interaction mechanism between coal powder and hot air is combined. Through the numerical simulation of the movement and combustion process of coal powder in the coal gun and the subsequent air duct branch and tuyere sleeve, starting from the macro and micro heat and mass transfer processes, with the goal of energy saving, emission reduction and saving equipment operation and maintenance costs, an evaluation index of coal powder movement and combustion behavior is established, a systematic evaluation of the ISF coal injection and blast combined injection mode is completed, and a comprehensive quantitative evaluation method for the injection mode is constructed.

[0031] This method combines the characteristics of the coal injection combustion process and computer numerical simulation to achieve a systematic evaluation of the coal gun layout of the closed blast furnace (ISF), which helps to strengthen the understanding of the coal injection process of the closed blast furnace, provide guidance for the optimization of the on-site coal injection combustion process, and provide a guarantee for the smooth progress of lead and zinc smelting in ISF.

[0032] Embodiment 2: Based on embodiment 1, this embodiment is described with a specific example.

[0033] like Figure 2As shown in the figure, the typical single coal gun layout of a lead-zinc closed blast furnace. As can be seen from the figure, the parameters that determine the layout of the coal gun are: the horizontal distance between the end of the coal gun outlet and the outlet of the hot air pipe; the inner diameter of the coal gun; the angle between the coal gun and the hot air pipe; and the insertion position of the coal gun in the hot air pipe.

[0034] According to actual production, the coal gun-hot air pipe arrangement of the example benchmark working condition 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°.

[0035] The numerical simulation calculation is carried out by taking the coal gun arrangement under the actual working conditions as an example. Figure 3 As shown, it is a numerical simulation physical model. The numerical simulation mathematical model of the hot air-coal powder two-phase reaction flow in the coal gun-air duct is shown in Table 1-2. Among them, the coal powder combustion process includes three stages: water evaporation, thermal decomposition of volatiles and their combustion, and residual carbon combustion. The mathematical models of each stage are diffusion control model, finite rate / eddy dissipation model and dynamic / diffusion model.

[0036] Table 1 Numerical simulation model of gas phase flow heat transfer

[0037] Table 2 Numerical simulation model of particle motion heat transfer

[0038] in, , are the fluid and particle densities, kg / m 3 ; , are the fluid velocity vector, m / s; is the average pressure of the fluid, Pa; , are the molecular dynamic viscosity and turbulent viscosity of the fluid, ; is time, s; for Gravitational acceleration in direction, m / s 2 ; is the particle mass, kg; is the particle mass change rate, kg / s. is the drag coefficient, Re is the Reynolds number, and Pr is the Prandtl number; , are the gas phase and particle temperatures, K, respectively; is the heat of reaction; is the particle specific heat, ; is the particle area, m2 ; is the emissivity of the particle; is the Stefan-Boltzmann constant.

[0039] The boundary conditions of the numerical simulation model are as follows. Figure 3 shown.

[0040] Table 3 Boundary conditions for numerical simulation of coal injection combustion

[0041] Furthermore, when the parameters of the coal gun-hot air pipe arrangement are: coal gun diameter 20mm; coal gun outlet is 310mm away from the hot air pipe outlet; coal gun angle 7°, that is, the angle with the hot air pipe is 5°; the bottom of the coal gun is inserted. The coal powder burnout rate and coal powder stratification diffusion degree of the baseline working condition and this working condition are shown in Table 4.

[0042] Table 4 Evaluation indicators of different working conditions

[0043] According to the results in Table 4, compared with the benchmark working conditions, when the parameters of the coal gun-hot air pipe arrangement are: coal gun diameter 20 mm; coal gun outlet is 310 mm away from the hot air pipe outlet; coal gun angle 7 degrees, that is, the angle with the hot air pipe is 5 degrees; when the bottom of the coal gun is inserted, the evaluation indexes of the stratified diffusion degree and the burnout rate of the coal powder are greater, the mixing of the coal powder and the hot air is more complete, and the pyrolysis state of the coal powder is better. At this time, the coal gun-hot air pipe arrangement is better.

[0044] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A comprehensive evaluation method for the arrangement of coal guns and hot air pipes in a closed blast furnace for lead and zinc smelting, characterized in that: S1. Determine the type of coal gun arrangement to be evaluated according to the coal gun-hot air pipe arrangement form parameters; S2. Establishing numerical simulation of coal injection combustion process of coal gun-hot air pipe; S3. Extract, analyze and evaluate indicators based on the distribution of multiple physical fields and the movement and combustion of pulverized coal under different working conditions; S4. Quantitative evaluation of the coal gun-hot air duct arrangement method. The evaluation method is: evaluate the coal gun-hot air duct arrangement method based on the two major indicators of coal powder burnout rate and stratification diffusion degree; the greater the coal powder burnout rate and the greater the stratification diffusion degree, the more reasonable the coal gun-hot air duct arrangement method is.

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

3. The comprehensive evaluation method for the arrangement of coal guns and hot air pipes in a closed blast furnace for lead and zinc smelting according to claim 1 is characterized in that: The numerical simulation of the coal injection combustion process of the coal gun-hot air duct in S2 includes establishing the physical model of the coal gun-hot air duct, the mathematical model of coal powder combustion and gas-particle two-phase flow, and determining the corresponding fixed solution conditions.

4. The comprehensive evaluation method for the arrangement of coal guns and hot air pipes in a closed blast furnace for lead and zinc smelting according to claim 3 is characterized in that: In S2, a numerical simulation physical model and solution conditions are established according to the blast and coal injection conditions, coal powder properties, coal gun and air duct sizes, and coal gun arrangement of the lower part of the lead-zinc closed blast furnace. The mathematical model is determined by combining the principles of air flow, coal powder movement and combustion, and phase interaction. Multi-level and multi-factor numerical simulation calculations are performed on the parameters of different coal gun-hot air duct arrangements to obtain the multi-physical field distribution of coal powder particles in coal guns and air ducts with different parameters and the coal powder movement and combustion conditions.

5. The comprehensive evaluation method for the arrangement of coal guns and hot air pipes in a closed blast furnace for lead and zinc smelting according to claim 1 is characterized in that: In S3, the evaluation indexes include the pulverized coal combustion utilization index and the pulverized coal particle diffusion index.

6. The comprehensive evaluation method for the arrangement of coal guns and hot air pipes in a closed blast furnace for lead and zinc smelting according to claim 5 is characterized in that: 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 the coal powder particles and the distribution of coal powder particles of different particle sizes.

7. The comprehensive evaluation method for the arrangement of coal guns and hot air pipes in a closed blast furnace for lead and zinc smelting according to claim 6 is characterized in that: The comparative analysis and evaluation method of coal powder combustion utilization index and particle diffusion index is as follows: the greater the burnout rate of the combustible part of the coal powder, the better the coal powder combustion utilization index; the greater the degree of coal powder stratification diffusion, the better the diffusion.

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