无钟高炉装料过程炉料运动分布规律及颗粒偏析行为研究

发布时间：2018-03-14 21:15

  本文选题：无钟高炉　切入点：炉料运动　出处：《北京科技大学》2017年博士论文　论文类型：学位论文

【摘要】：当前,在钢铁工业节能减排和制造业升级背景下,要求实现高炉高效低碳冶炼以及精细化操作控制,优化改善高炉操作成为重点之一。上部装料制度作为高炉四大操作制度中最灵活和最常用的调剂手段,决定着炉内的炉料颗粒分布状况,进而影响炉内煤气流分布,对促进高炉顺行、提高煤气利用率、降低燃料比等有着重要作用。目前广泛使用的高炉无钟炉顶主要分为串罐式炉顶和并罐式炉顶,两者装料规律差异巨大,并罐式炉顶装料过程炉料运动分布规律更加复杂,且已有研究尚存不足；另一方面,高炉装料过程中炉料既以宏观整体料流形态运动分布,又存在着微观上不同粒径和不同种类颗粒间偏析分布,而长期以来对后者研究认识不足。因此,在前人研究工作基础上,本文针对串罐式和并罐式无钟高炉装料过程分别运用机理建模方法和离散元仿真方法对炉料宏观运动分布规律和微观颗粒偏析行为进行了系统的研究分析,为后续高炉炉顶设计选型及生产操作实践提供了参考依据和理论指导。主要研究内容及结果如下：(1)考虑到串、并罐无钟炉顶以及不同型式溜槽布料差异性,通过分析炉料运动受力状况,建立了节流阀出口处炉料流速数学模型、节流阀至溜槽间炉料运动数学模型、多环布料过程中半圆形截面溜槽和矩形截面溜槽内炉料运动三维数学模型、空区内料流轨迹及料流宽度数学模型、炉料落点及瞬时流量数学模型和料面形状数学模型,并通过1：7布料模型实验验证了所建立数学模型的准确性与可靠性。其中,首次针对并罐式炉顶常用的弧形闸板,阀建立其排料时炉料流速数学模型,定量计算出并罐布料时炉料分别在半圆形截面溜槽和矩形截面溜槽内的落点轨迹形状,指出前者为非椭圆状、后者为椭圆形,同时考虑了多环布料时溜槽水平圆周旋转和倾动的复合运动特点,可计算环形布料和螺旋布料工况。(2)利用本文开发的布料综合数学模型分别计算分析了炉顶设备结构参数和高炉生产相关参数两类主要影响因素对炉料运动分布影响,前者主要包括无钟炉顶型式、中心喉管内径、溜槽悬挂点高度、溜槽倾动距、溜槽长度、溜槽截面形状等,后者则主要包括炉料种类、并罐“倒罐”模式、节流阀开度、溜槽倾角、溜槽转速、溜槽转向、料线高度、煤气流速等。结果表明：并罐式高炉布料时同时存在料面炉料落点和瞬时流量圆周偏析；溜槽悬挂点高度、溜槽倾动距、溜槽长度、溜槽倾角和料线高度主要影响炉料落点远近,对并罐布料炉料落点和流量圆周偏析程度影响较小；减小中心喉管内径和增大节流阀开度均能有效降低并罐布料炉料落点和流量圆周偏析程度；相比半圆形截面溜槽,矩形截面溜槽对应的料流宽度较小、料流更加集中,在料面上的落点半径和流量圆周偏析程度也更低；溜槽转速或煤气流速增大不仅使炉料落点半径整体增大,还将加重并罐布料流量偏析；并罐布料时改变“倒罐”模式和溜槽转向将使炉料落点和流量圆周分布曲线分别与原曲线关于高炉中心和0°-180°线对称分布,因此能够在一定程度上弥补炉内偏析程度。(3)基于离散单元法建立了离散炉料颗粒运动数学模型,分别针对实际4350m3串罐式无钟高炉和5500m3并罐式无钟高炉从料仓至炉喉的整个装料过程进行了仿真研究,分析了各环节内微观颗粒偏析行为,并利用串罐高炉开炉实测结果验证了仿真模型的可靠性。研究发现,炉料颗粒间偏析分布现象贯穿于整个装料过程中,在皮带料层厚度方向存在大小颗粒偏析分布,在串罐式炉顶的上、下料罐和并罐式炉顶的左、右料罐内颗粒分布也不均匀;料罐排料时,罐内炉料呈“漏斗流”,排料前期颗粒平均粒径较小、后期较大,末期则有较多小颗粒排出,导料锥存在能够减小串罐排料时颗粒粒度变化幅度；炉料颗粒在溜槽内会发生偏转,对于并罐式高炉布料,溜槽位于不同方位时其内部颗粒运动状况不同；在炉喉内,主要是径向和纵向上颗粒平均粒径变化较大,周向偏析较小,但并罐式高炉装料时,炉喉周向还存在炉料体积分布不均现象。
[Abstract]:At present, the upgrade background in iron and steel industry energy-saving emission reduction and manufacturing, to achieve high efficiency and low carbon requirements of blast furnace smelting and fine operation control, optimization and improvement of blast furnace operation has become the focus of one of the top charging system of blast furnace. As the four operating system is the most flexible and most commonly used means of regulating agent, determines the distribution of charge particles in furnace then, effect of gas flow distribution in the furnace, to promote the smooth operation of blast furnace, improve the utilization rate of gas, reducing fuel ratio plays an important role. The widely used blast furnace bell less top is divided into series tank top and a tank top and two charging rules, huge, and tank top charging process of charge movement distribution is more complex, and the existing research still insufficient; on the other hand, in the process of charging of blast furnace burden both to the overall flow of movement patterns and the presence of the microscopic distribution of different particle size and With the segregation of species distribution between particles, and for a long time to the study of lack of knowledge. Therefore, based on the previous research work, this paper on the tank and tank bell charging process using mechanism modeling method and discrete element method of system simulation research has carried on the analysis to the macro and micro motion charge distribution particle segregation behavior, provide reference and theoretical guidance for the subsequent blast furnace design selection and production practice. The main research contents and results are as follows: (1) taking into account the string, and bell furnace top and different types of distribution chute differences, through the analysis of charge movement stress condition, established the outlet throttle valve charge flow mathematical model, the throttle valve to the chute between charge movement mathematical model, a three-dimensional mathematical charge movement semi circular section and rectangular section chute chute ring charging model, The empty area material flow and material flow path width model, charge placement and instantaneous flow mathematical model and mathematical model of surface shape, and the accuracy and reliability of the mathematical model is verified by experiments. The 1:7 distribution model for the first time, the arc gate and the tank top is used, the discharge valve is established when the charge flow mathematical model, quantitative calculation and cloth respectively in charge tank semi circular section and rectangular section chute chute of the landing trajectory shape, pointed out that the former is non elliptical, the latter is oval, considering the rotation and tilting chute horizontal circumferential motion characteristics of polycyclic composite cloth and cloth cloth can be calculated ring and spiral case. (2) using a comprehensive mathematical model of cloth is developed in this paper to calculate the factors of structural parameters and blast furnace top equipment production related parameters of two kinds of effect on furnace material transport The dynamic distribution of influence, the former mainly includes the type of bell less top, center pipe diameter, the suspension height chute, chute tilting distance, the length of the chute, chute cross-section shape, the latter mainly includes the furnace type, and tank "tank" mode, the throttle valve opening, chute, chute, chute feed speed, steering, line height, gas velocity. The results show that the tank and the blast furnace burden when exist at the same time charge placement and instantaneous flow circumferential segregation; the suspension height chute, chute tilting distance, the length of the chute, chute and feed line height mainly affected placement distance has little effect on the charge, and can charge cloth placement and flow circle segregation the center pipe diameter and increase; reduce the throttle valve opening can effectively reduce the burden of cloth and tank placement and traffic circle segregation; compared with semi circular section chute, rectangular chute corresponding stream width 搴﹁緝灏，

本文编号：1612968