Flow of materials in rotary kilns used for sponge iron manufacture: Part III. Effect of ring formation within the kiln

The formation of accretions or ’rings’ in rotary kilns used for the manufacture of directly reduced iron (sponge iron) affects the residence time of the charge, kiln hold-up, and the kiln output to a great extent. In this part of the work, the effect of ring formation was simulated at room temperature in a scaled-down model of a rotary kiln by inserting conical dams in the shape of frustrums of cones through the feed end of the kiln. The influence of such conical dams on various operating parameters was evaluated.     

球团回转窑建模与仿真的研究进展

摘要：回转窑是一种高温处理物料的热工设备,充分了解回转窑内发生的物理与化学变化对生产具有指导意义,而人眼观察或利用仪器等方式难以探查窑内情况。为掌握回转窑内处理物料的情况并提高生产效率,国内外利用建模与仿真的方法模拟回转窑结构、窑内热场、物料运动。现有模拟已经涉及到了回转窑整体、窑壁、耐火材料、烟气、燃料、火焰、物料等,并利用建模与仿真结果研究了回转窑结构参数及生产参数对部分现象的影响。根据窑内不同区域,综述了回转窑建模与仿真的进展,汇总了建模与仿真的方法与过程及部分参数对回转窑生产的影响。回顾与分析现有的回转窑建模与仿真成果,有助于优化回转窑设备结构的设计及回转窑生产。     

Residence time distribution and material flow studies in a rotary kiln

Experiments were conducted in a rotary kiln containing ilmenite particles to study the residence time distribution (RTD) of low-density particles, holdup, and bed depth profile. The variables include feed rate of solids, slope and rotational speed of the kiln, type and size of the tracer, and dam height. Correlations are presented for mean residence time, dispersion number, holdup, and steady-state throughput of solids in terms of the process variables. A simple method is proposed to estimate the dam height that gives rise to a flat profile of solids bed along the length of the kiln.     

Flow of materials in rotary kilns used for sponge iron manufacture: Part I. Effect of some operational variables

Looking forward to the need of developing coal-based sponge iron technology in India, a country having no significant resources of either coking coal or natural gas, the Research and Development Division of the Tata Iron and Steel Company Limited (TISCO) set up a rotary kiln based direct reduction pilot plant in 1975. In this pilot plant, a totally indigenous technology for production of sponge iron has been developed in which non-coking coal is essentially used as the reductant. For easy scaling up of the TISCO Direct Reduction (TDR) process to units of 300 to 400 tpd capacity, it was thought necessary to explore some of the fundamental aspects of material flow in a rotary kiln. This was carried out by studying the flow of materials in room temperature models. The work was divided into two parts: first, a study of the influence of several operating parameters,viz., rotational speed, inclination of the kiln, effect of circular dams at the feed and the exit ends of the kiln,etc., and second, an investigation of the extent of segregation of a mixture of solids in a rotating kiln. The highlights of the experimental results dealing mainly with the effect of various kiln operating variables on the filling degree profile of the charge in the kiln are presented. Formerly Joint Director, Research and Development, TISCO Formerly with TISCO, Jamshedpur     

回转窑无管供风煅烧技术的探讨

以φ2.3x55 m的炭素回转窑作为研究对象,对回转窑内的煅烧过程进行了数值计算.通过多次改变二、三次供风管的长度,得到了相应条件下窑内的温度分布,并进行了比较和分析.结果表明:二、三次供风管的长度对窑内温度场的影响较小,实践中可以采用无管供风措施,以解决供风管道烧损问题.     

回转窑调整的定性定量分析

分析了影响回转窑直线度的各种因素及调整所需测量的数据,对各种情况下回转窑中心线偏移进行了定性定量分析,总结出经验公式,对现场回转窑调整具有实际指导意义。     

回转窑恒定给料的生产实践

采用回转窑焙烧是钼加工广泛应用的方法。影响焙烧作业效果的因素诸多,回转窑持续、均匀给料就是其中重要的一项因素。德兴铜矿在钼加工生产实践中,加强钼精矿水份控制,同时引进由粉料气力输送及失重秤螺旋定量给料组成的全自动恒定给料系统,并在使用过程中对系统予以改进,有效地促进了回转窑恒定给料,提高了焙烧作业效果。     

回转窑关键部件大型简体加工工艺设计

回转窑是一种大型圆筒类回转设备,简体是回转窑的重要组成部件,本文着重论述了回转窑简体在下料、钢板预处理、简体拼接、焊缝质量卷制、坡口设计、简体加工等方面关键部位的工艺保障措施,选择先进的新工艺、新方法解决回转窑生产过程中的技术难题,为回转窑的顺利生产提供了有效的技术支持和保障。     

浅谈回转窑节能降耗窑衬

本通过对回转窑节能降耗窑衬的介绍，说明在回转窑上，根据不同的段带采用不同的隔热窑衬，既能起到节能降耗的目的，又能保证回转窑窑衬安全高效运行，具有很好的经济效益。     

直接还原回转窑测温系统存在的问题及对策

温度是回转窑最重要的工艺参数,对回转窑产量、质量起决定性作用,同时还影响回转窑的能耗、运转的稳定及其寿命。文章介绍了针对回转窑测温系统的技术改造,使得回转窑测温系统更趋完善,为回转窑操作提供了参数保障,但仍需进一步改进,以便更好地指导生产。     

Regenerative heat transfer in rotary kilns

A mathematical model has been developed to determine the temperature distribution in the wall of a rotary kiln. The model, which incorporates a detailed formulation of the radiative and convective heat-transfer coefficients in a kiln, has been employed to examine the effect of different kiln variables on both the regenerative and the overall heat transfer to the solids. The variables include rotational speed, pct loading, temperature of gas and solids, emissivity of wall and solids, convective heattransfer coefficients at the exposed and covered wall, and thermal diffusivity of the wall. The model shows that the regenerative heat flow is most important in the cold end of a rotary kiln, but that generally the temperature distribution and heat flows are largely independent of these variables. Owing to this insensitivity it has been possible to simplify the model with the aid of a resistive analog. Calculations are presented indicating that both the shell loss and total heat flow to the bed may be estimated to within 5 pct using this simplified model.     

采用气态悬浮焙烧技术改造老式回转窑

鉴于国内氧化铝厂氢氧化铝焙烧都引进了国外先进的流态化技术装置，原焙烧用的回转窑现基本处于闲置状态，为了利用老设备，我们正在研究改造这些老式回转窑的办法，本以长城铝业公司氧化铝厂2＃回转窑为例，对上次改造作了总结分析，经过多次深入现场调查研究，结合气态悬浮焙烧技术原理，提出了一种新的改造方案，我们认为采用这种方案具有投资少，见效快，回报率高的特点。     

炭素回转窑内煅烧石油焦热物性参数的测试与研究

影响回转窑煅烧过程的因素有许多，其中物料所含水分、灰分、挥发分的含量、成分及其在某一温度段的逸出规律等对回转窑的煅烧工况有着重要的影响，因此本实验测试了煅烧过程中石油焦热物性参数随温度的变化规律，挥发分燃烧的特点，为回转窑内煅烧工况的研究提供参考依据，使其煅烧过程优化，达到高产、优质和低消耗的目的。     

Coal pyrolysis in a rotary kiln: Part II. Overall model of the furnace

In order to simulate coal pyrolysis in a rotary kiln in the steady-state regime, a mathematical model has been developed which calculates the temperature profiles in the charge, the gas, and the furnace walls, together with the gas composition and the degree of removal of volatile species. The model takes into account the principal physicochemical and thermal phenomena involved, including the complex movements of the charge; the gas flow; heat transfer between the charge, the gas phase, and the furnace walls; drying and pyrolysis of the coal; the cracking of tars; the combustion of volatile species; and the combustion and extinction of the coke. The data necessary for the model were obtained by specific experiments or from the literature. The model has been validated by comparing its predictions to measurements performed on an industrial rotary kiln. The model has been used to study the influence of operating parameters such as the furnace rotation speed, in order to optimize the process. It is shown how a modification to the extinction zone leads to an increase in coke yield of 0.75 pct.     

基于时序趋势特征的回转窑喂煤SVM分类方法

提出一种基于时序趋势特征的回转窑喂煤支持向量机（SVM）分类方法,根据回转窑多个热工数据之间的动态变化规律预测喂煤变化趋势,指导人工喂煤调节的操作。首先对回转窑热工数据进行预处理,将喂煤时间序列分段线性表示,并提取相应趋势特征,形成训练样本;然后采用粒子群（PSO）算法优化SVM参数,构建SVM分类器,进而对测试样本进行分类,实现对喂煤趋势的分类预测。通过采用现场数据进行对比分析,证明本文提出的喂煤趋势预测方法具有较高的预测准确率,提高了窑前控制的鲁棒性,模型达到了现场应用的水平。     

氧化铝回转窑内物料流动与传热数值模拟

在分析氧化铝回转窑传热过程的基础上,运用多相流理论对回转窑内横截面物料流动与传热过程进行数值模拟,研究了不同工况下横截面上的温度分布及流动情况。结果表明,截面上物料温度主要受气体及窑壁传热影响,物料颗粒越小,其内部温度上升越快,流动带起的物料高度也越低,但截面上物料内部温度分布基本趋于一致,并可忽略截面温差。     

煅烧白云石质量的影响因素分析与控制

结合回转窑煅烧白云石生产实际进行跟踪试验,分析研究了白云石粒度、煅烧时间、煅烧温度对白云石质量的影响,为实际白云石煅烧生产提供了较佳的煅烧条件。同时提出了以回转窑主电机转速进行煅烧时间的控制;以窑尾温度和感应温度计所测窑壁温度来控制煅烧温度的控制措施,并在生产中得到了应用。     

球团矿回转窑衬破损原因探讨

对生产球团矿用回转窑衬破损的原因进行分析,认为回转窑内耐火材料的破损主要在窑头部和窑中部,这两个部位窑外表温度高,窑内结瘤多;窑内铆固件设置不合理,预制砖、下料口炉墙浇注料的结构与性能不匹配,浇注料的施工、烘烤工艺的影响是回转窑破损的主要原因。     

影响外加热式回转窑炉龄探析

结合外加热式回转窑焙烧钼精矿的生产工艺与实践，分析了影响回转窑炉龄的因素，旨在寻求延长回转窑炉龄的有效途径，以降低企业的生产成本，提高经济效益。     

球团厂回转窑冬季焊接施工技术分析

球团厂回转窑材质多为20G,焊接施工比较复杂,安装工期较长,往往需要跨年度施工.由于气候的原因,回转窑冬季焊接时,必须考虑施工技术及相应的焊接防护措施.为保证焊接质量,针对国产锅炉用钢板20G的焊接特点,以及回转窑的安装特点,应首先确定冬季焊接工艺,然后选择合理的焊材,在焊前进行相应的预热,并在焊后进行适当的保温等.