可描述高炉内液流分布的数学模型

 高炉内液体流动现象的研究对控制高炉工艺过程具有重要意义。针对液流由非润湿液滴组成、惯性力对运动方向影响可忽略、垂直运动方向上有质量交换等高炉内液体运动的特点,采用合适的假设,建立了一个可描述高炉内液流分布的数学模型。该数学模型以整个填充床区域为求解范围,其数值求解网格尺度仅满足数值精度即可,不必和床层填充颗粒尺寸相一致。模型预测结果和实验数据有较好的一致性。高炉模拟中本模型是一个可供选择的模型。     

高炉条件下填充床内液体运动规律的数学模型

 目前高炉条件下，填充床内液体动量传输现象的研究结果或者存在工程应用上的障碍，或者存在模型内容上的缺陷。描述了填充床层对液流的阻力和分散2种作用，从而建立一个新的非稳态模型。经实验数据验证和与其它模型对比分析，建立的模型更适合对高炉等炼铁工艺的模拟。     

填充床中气体流动特性的数值研究

以SIMPLE算法编制了数值求解描述填充床内气体运动规律的Ergun方程的程序,就不同的气体入口设置高度、不同的气体流入床层方式、不同床层结构计算了填充床内的速度场和压力场。结果表明：只要入口距出口足够远,出口及与其相连的床层内大部分区域的流场在不同气体流入方式下是相同的,通过模拟计算获得的对进风口设置高度的认识、非均匀床层中气体流动规律的认识对高炉工艺有借鉴意义。     

崩落散体流动空位填充法及其应用

基于随机理论,结合力学判据,提出散体流动空位填充法,并给出模型建立规则和方法,简化散体之间的力学关系,为崩落矿岩流动规律的研究提供新的方法;同时基于空位填充法,研发了二维放矿仿真系统（VFMS）,并利用该系统对不同结构参数进行放矿仿真试验,得出的结果符合放矿规律,说明利用空位填充法模拟散体流动是可行的。     

高炉内型对炉内状态的影响

调查了高炉内型对操作的影响.采用数学模拟模型进行了研究.该模型能够分析如下操作条件:压差、燃料比和炉况稳定性(防止管道行程).在高炉内容积、有效高度和炉缸直径等数据的基础上,评价了大量的高炉内型数据.在这次调查过程中,弄清了炉型几何参数对高炉状态的影响,并给出了较佳的参数值.     

高炉矿焦床层孔隙分形维数的计算机模型研究

在计算机模拟高炉矿、焦床层分形结构的基础上,引入了2个参数:散料颗粒的形状系数φ与内孔隙度ε对模拟结果进行了修正,分析了影响散料层孔隙度与孔隙结构分形维数的因素.研究结果表明,随着散料层孔隙度的增加,孔隙结构的Sierpinski分形维数增大,孔隙对散料层的填充能力增强.     

COREX熔化气化炉稳态数值模拟

基于多相质量守恒、动量守恒和热量守恒开发了一维稳态的数学模型,对熔化气化炉填充床进行模拟,自由空间和风口区则采用静态平衡来进行计算.计算得出的渣铁温度、炉顶煤气温度及成分与工厂报道值相吻合.应用该模型能够研究床层高度、原料的成分和操作参数等对工艺过程的影响.     

填充床鼓泡电化学反应器行为特性研究：I.丙烯阳极直接氧化的数学模拟

本文建立了填充床鼓泡电化学反应器的一维数模，该模型考虑了反应动力学，也考虑了体系的基本传递特性，模拟结果可以描述床层径向电势，电流和浓度分布。     

高炉内细微颗粒静态停滞数值分析

随着高炉喷煤比的提高，将会产生大量未燃煤粉颗粒和碎焦，破坏高炉内料柱的透气性。因此，了解填充层内粉末流动特性的重要性日益增加。尽管已经有了关于填充层内粉末的动态或完全停滞状态特性的报道，但是对高炉内粉末的动态和停滞状态行为采取分别处理的方法还未见报道。在本文中，利用包含粉末静态特性公式的“四流体模型”，通过数值模拟，对粉末的静态行为进行了测试。模拟结果与三种不同喷煤比（100、200和250kg／t）条件下测得的炉内二维温度分布情况进行了比较，以求验证。该模型可用于高喷煤比操作条件下对炉内粉末静态停滞进行定量分析。在100、150、200和225kg／t不同喷煤比条件下，大量粉末静态停滞分别出现在中心死料柱下部、风口平面上方和下方以及炉身上部，有少量的粉末静态停滞在回旋区域，遍及死料柱表面。     

包钢富氧喷煤工艺参数计算分析

文章针对“七五”重点科学技术攻关项目——高炉富氧喷煤工业试验,建立了富氧喷煤工艺参数计算数学模型。该模型简单、明了、实用,以高温区碳、氧和热平衡为基础,计算工艺参数为目标。在对工艺参数进行回归分析的基础上,指出了高炉富氧喷煤适宜的工艺参数以及各参数之间的相互关系。对高炉富氧喷煤操作有重要的指导作用。     

Nonwetting flow of a liquid through a packed bed with gas cross-flow

In this study, the effect of a cross-flow gas field on the percolating flow of a non-wetting liquid through a packed bed was investigated. Experiments were conducted to measure the liquid shift, due to the cross-flow of air, for the flow of aqueous barium chloride solutions and mercury percolating through beds of polyethylene and expanded polystyrene particles. An X-ray technique was used to visualize the liquid flow pattern through the packed bed. The liquid percolates through a packed bed as a series of rivulets and droplets which are continuously breaking up and coalescing. A mathematical model to predict the direction of the liquid rivulet/droplet flow under the influence of a gas flow field was developed. The model treats the liquid as a discrete phase and includes the effects of gravity, gas drag, and inertial and viscous bed resistance. The effective droplet/rivulet size is an important model parameter, and the model postulates that the droplet/rivulet size is a function of both the effective capillary size of the bed and the liquid flow rate. A simplified population balance analysis for droplet coalescence is used to predict the effect of liquid flow rate on droplet/rivulet size. The model predictions are consistent with the experiments.     

Modeling the discontinuous liquid flow in a blast furnace

This article presents a mathematical model to describe the discontinuous flow of an isothermal liquid in packed beds, simulating in part the flow condition in and below the blast furnace cohesive zone. The model is developed based on a force balance approach to describe the discrete liquid flow and a stochastic treatment to take into account the complex packing structure. The interaction between gas and liquid flows has also been included in the governing equations, so that the localized liquid flow in a packed bed can be modeled with or without gas flow. The difference between the microscopic and macroscopic approaches is discussed, and it is argued that at this stage of development, liquid flow modeling should be conducted at the macroscopic level. Techniques for numerical solution are provided. The validity of the proposed model is demonstrated by comparing model predictions with measurements obtained using a two-dimensional cold model apparatus under different gas and/or liquid flow conditions.     

Calculation and Analysis of Liquid Holdup in Lower Blast Furnace by Model Experiments

A hydromechanics experiment on the countercurrent flow of gas and liquid simulating the flow conditions in the lower blast furnace was carried out. A cold model of a packed bed with various packing materials and liquids was used to study the holdup of liquid. Correlations for static holdup, dynamic holdup, and total holdup were obtained. A good agreement was found between the calculated and experimental data. A mathematical model simulating the flow fields was applied to study the effect of liquid holdup in blast furnace. The results of the model calculation show that static holdup is the determinant of the total holdup of molten materials when the blast furnace works in stable condition. The slag phase generally reaches flooding holdup ahead of the hot metal. The radial distribution of gas flow is almost not influenced by the holdup of molten materials, but it has a greater influence on the pressure drop. The size of coke has far greater influence on static holdup than liquid properties does. The study is useful for acquiring a deeper understanding of the complex phenomena in the blast furnace and for determining appropriate operational actions under different production conditions.     

The Removal of Finely-divided Particles by Liquid Beds

Abstract

The removal of finely-divided prticles in alumina, silica and coal particles of average size of 5 microns in diameter has been investigated utilizing liquid fluidized and packed beds. The bed particles used included 40×100, 100×150 and 150×200 mesh silica and corundum particles. Important variables examined included surface charge, flow rate, pH and amount of bed particles

A mathematical model describing the concentration profile of fine particles in the axial direction in liquid fluidized beds has also been developed. The equation of continuity was solved using a forward finite differentiation technique. The application of this model to the scale-up investigation was discussed

The recovery of silica and coat fines was possible on corundum bed particles, while alumina fines was possible on silica beds as well as corundum bed particles due to electrostatic and van der Waals attractive forces. Fine particle recovery wasdirectly proportional to the total surface area of bed particles. The possibility of recycling bed particles after desorption of adsorbed fine particles was also studied.     

Some Studies to Establish the Reaction Mechanism for the Reduction of Iron Ore‐Graphite Composite Pellets in a Packed Bed Reactor

In this article an attempt has been made to propose a reaction mechanism for the reduction of iron ore‐graphite composite pellets in a packed bed reactor through experiments and mathematical models developed by the authors previously, along with some new supportive experimental data. A tailor made thermo‐gravimetric setup with a provision of packed bed has been developed to carry out isothermal experiments at elevated temperature and in controlled atmosphere. A kinetic model that calculates the evolution of various phases of iron oxides and a thermal model that calculates the temperature at the surface and centre of the cylindrical packed bed have been used along with experimental data under different operating conditions to formulate the reaction mechanism. It is proposed that reduction of iron ore‐graphite composite pellets in packed bed is initially heat transfer controlled and become mass transfer controlled at the later stage of reduction. The role of heat and mass transfer has been ascertained by observing the effect of C/Fe₂O₃ molar ratios, size of pellets, and CO gas in reactive atmosphere on the extent of reduction and the predicted temperature gradient, carbon consumption rate within the packed bed during the course of reduction.     

The investigations of gas‐powder two phase flow in packed bed

Gas‐powder two‐phase flow in packed beds was investigated and the results are presented in this paper. The experimental system, in which the glass powder and air gas were injected into the lower part of the packed bed allowed the estimation of the influence of gas velocity, powder feed rate, powder and packed particles diameter on pressure loss and total hold up of powder in the packed bed. On the base of the experimental results, a one‐dimensional mathematical model for gas‐powder two‐phase flow in the packed bed was developed. This model allows satisfactory prediction of the pressure loss and the hold ups of powders. The maximum deviation between calculated and measured values was less than ±15%. Futhermore, the conditions when the blockade of the flow occurs were defined. The additional pressure loss (expressed by F_k) due to the gravitional force of powders and the collision and the friction between powders and packed particles, was correlated with Froude number as: for the void fraction in the packed bed ?₀ of between 0.36 to 0.41 or .