过量空气系数及喂煤量对回转窑温度分布影响

在对回转窑已有传热研究基础上,进一步考虑了水泥回转窑煤粉燃烧和窑内化学反应,建立了计算回转窑温度分布的综合数学模型;基于此模型利用Matlab软件编程研究过量空气系数和喂煤量对回转窑温度分布的影响,得出了过量空气系数和喂煤量对窑内烟气、物料和筒体外表面温度分布的影响规律。并将计算所得的窑筒体外表面温度分布与实测值相比较,两者具有较好的一致性,验证了所建立的回转窑温度场计算模型的有效性。     

富氧燃烧条件下钢坯加热特性的数值模拟

以某轧钢厂步进式加热炉为研究对象,利用Fluent软件对炉内气相流动与燃烧和钢坯加热过程建立数学模型,并开发了用户自定义函数处理钢坯移动。炉膛内气体流动采用Realizable k-ε模型,燃烧过程采用非预混燃烧模型,辐射传热采用DO模型来计算。通过所建立的数学模型,模拟研究了氧气体积分数为21%～35%的助燃气体与燃料燃烧对钢坯加热特性的影响。结果表明,随着氧气浓度的增加,燃烧区的烟气温度逐渐升高,导致钢坯具有更快的升温速率;由于富氧燃烧在燃烧区产生了更均匀的温度场,因此在氧气浓度为35%时,钢坯的黑印温差仅为15 K,比空气工况下的黑印温差低了20 K;当助燃气体中氧气体积分数从21%增加至35%时,钢坯的辐射传热量也随之增加,加热炉热效率从41.1%提高至48.4%。     

蓄热式钢包烘烤热行为的数值模拟和[NOx]排放特性

为了研究蓄热式钢包烘烤的空气和煤气的预热温度对高温空气燃烧过程的影响,耦合了烘烤过程中流体流动、换热和燃烧过程,用数值模拟方法建立了三维立体数学模型,利用计算流体力学软件Fluent,采用有限元差分法和修正速度—压力相耦合的算法Simple,计算了钢包内的燃烧现象,得出了在不同预热温度时,燃烧室内气体温度场和氧气浓度场的分布。结果表明,提高气体预热温度有利于加快燃烧进程,可提高炉内的整体温度及温度的均匀性,降低局部氧浓度,利用高的烘烤效率减少[NOx]的排放。     

45m煅烧回转窑燃烧控制系统设计与实现

介绍了通过应用红外扫描、氧含量分析仪开发应用45m回转窑燃烧控制系统,实现煅烧带参数变化趋势;实时监测并报警;并可通过回转窑燃烧控制辅助管理系统,实现手动/自动控制的无扰切换功能.     

复杂金泥、铜阳极泥混配处理技术研究及应用实践

介绍了恒邦股份公司采用回转窑焙烧处理金泥、铜阳极泥的工艺技术及生产实践,并对工艺改进、指标优化进行了探讨。实践证明,采用回转窑处理金泥、铜阳极泥工艺具有对原料适应性强、设备先进、综合回收率高、生产成本低、环境污染少等优点。     

Kinetics of oxidation roasting of molybdenite with different particle sizes

The kinetics of oxidation roasting of molybdenum concentrate was studied by differential thermal? gravimetric experiments and non-isothermal analysis methods. The results show that high temperature is beneficial for oxidation of molybdenum concentrate. The initial oxidation temperature of the molybdenum concentrate is 450 °C, and the rapid oxidation occurs above 500 °C. The oxidation process conforms to the unreacted shrinking nucleus model. The early stage of the oxidation is controlled by chemical reaction with the apparent activation energy of 123.180 kJ/mol, while the later stage is controlled by internal diffusion with the apparent activation energy of 80.175 kJ/mol. Moreover, the oxidation rate is closely related to particle size of the concentrate. The smaller the particle size is, the larger the oxidation rate is.     

大型石油焦回转窑煅烧过程三维数值模拟

通过采用商业软件Fluent12.1建立了大型石油焦回转窑窑内煅烧过程三维数值模拟模型,获得了在正常操作状态下窑内温度场、流场和物质浓度场的分布状况。计算结果显示,由于窑尾变径的影响,窑尾气流速加快,影响石油焦粉料的带出;窑内石油焦的升温速度较快,导致挥发分在靠近窑尾段大量析出,窑尾温度偏高,大量挥发分没有及时在窑内完全燃烧;由于窑头漏风的影响,造成煅烧带炭质烧损的增加。     

微波活化焙烧辉钼矿生产低硫氧化钼

对比研究了微波功率、作用时间及物料质量对辉钼矿预活化焙烧后的脱硫效果的影响,并采用气-固多相反应的未反应收缩核模型研究了辉钼矿氧化焙烧的动力学。结果表明,辉钼矿的吸波性能良好,在微波功率0.64 k W、物料质量30 g、微波作用6 min的条件下,微波可比常规处理方式显著降低硫含量0.256%;辉钼矿氧化焙烧是强放热反应,温度越高,辉钼矿氧化速率越快;540~630℃时转化率明显增高,界面化学反应是控制性环节。微波对于辉钼矿在常规氧化焙烧之前的活化作用已得到试验验证,若应用于工业生产,可采用短时间活化焙烧预处理来辅助常规的氧化焙烧。     

基于图像处理及模式聚类的二次仿真方法及其在回转窑温度监控中的应用

提出一种基于图像处理和模式聚类的二次仿真方法。应用Fluent商业软件对回转窑内粉煤在27类设定工况的燃烧进行温度场的三维数值模拟,将仿真结果构建仿真结果数据库;采用模式聚类的方法判断实际工况属于哪一类标准工况,调用仿真结果数据库建立温度与该类标准工况的数学模型,求解模型并计算实际工况下的温度场;利用图像处理中的伪彩色变换得到二次仿真结果,用VC＋＋6.0来实现。结果表明：该方法能够较准确地给出仿真结果,极大缩短计算时间,为回转窑内温度监测提供一种新思路,具有较大的现场应用价值,并很容易推广到其他领域中。     

余热利用技术在热轧无缝钢管机组中的应用

以某159 mm连轧管机组工程为例,着重介绍了环形炉烟气余热利用技术在生产实践中的应用情况和使用效果,以推动余热综合利用技术在此领域的进步。     

Korrosion in Rauchgasen bei 1000 °C

Corrosion in flue gas at 1000 °C An improvement in efficiency of coal combustion power plants can be achieved by the combined cycle process with gas and steam turbines. The effective power is also optimized if the energy generated in the boiler is discharged by utilizing a liquid sodium heat exchanger, working at a temperature of 1000 °C. In this case the heat exchanger materials are exposed to severe conditions. Liquid sodium at a temperature ranging up to 1000 °C flows through the heat exchanger tubes and the outer surface of the tubes is exposed to the flue gas. The materials are stressed mechanically and are also subjected to high temperature corrosion. Therefore high temperature corrosion tests were carried out with Fe-Ni-Cr- and Ni-base alloys in a laboratory furnace in which the alloys are exposed to the flue gas at a temperature of 1000 °C for a total period of 3000 h. The experiments have shown that most of the materials have a sufficient resistance to weight loss corrosion but in some cases severe internal oxidation occurs. This kind of corrosion is mainly observed for materials with high concentrations of elements such as aluminium, silicon etc., i.e. by the elements with very high negative values of free energy of formation of oxides.     

Coal Combustion Behavior in New Ironmaking Process of Top Gas Recycling Oxygen Blast Furnace

The top gas recycling oxygen blast furnace (TGR-OBF) is a new ironmaking process which can significantly reduce the coke ratio and emissions of carbon dioxide. To better understand the coal combustion characteristics in the TGR-OBF, a three dimensional model was developed to simulate the lance–blowpipe–tuyere–raceway of a TGR-OBF. The combustion characteristics of pulverized coal in TGR-OBF were investigated. Furthermore, the effects of oxygen concentration and temperature were also analyzed. The simulation results show that the coal burnout increased by 16.23% compared to that of the TBF. The oxygen content has an obvious effect on the burnout. At 70% oxygen content, the coal burnout is only 21.64%, with a decrease of 50.14% compared to that of TBF. Moreover, the effect of oxygen temperature is also very obvious.     

烧结法氧化铝新型煤粉制备线设计与应用

针对烧结法氧化铝生产用高挥发分煤粉的特点，结合原有老线安全环保问题，研究设计了新型煤粉制备线，重点论述了工艺技术创新和安全环保措施，对比分析了新线的运行经济效苴。与老线比较。工艺先进。节能降耗，安全环保。     

Recovery of rhenium from molybdenum and copper concentrates during the Looping Sulfide Oxidation process

Rhenium is recovered during pyrometallurgical processing of molybdenum sulfide and copper sulfide ores; the traditional technology involves removing rhenium(VII) oxide, Re₂O₇, from the sulfurous gas phase generated during multiple hearth roasting (in molybdenum processing) and smelting (in copper processing). A new technology platform called Looping Sulfide Oxidation (LSO) has been proposed to produce molybdenum and copper using alternative process chemistries. A detailed thermodynamic study of the reaction conditions used in LSO process indicates that rhenium recovery is possible at higher rates than currently realized in the industry. Conditions at which Re₂O₇ is reduced to rhenium metal by S₂ have been identified and key process conditions are outlined to maximize performance of the LSO scheme and rhenium recovery.     

Oxidation Behaviors of Different Grades of Ferritic Heat Resistant Steels in High-Temperature Steam and Flue Gas Environments

For steam tubes used in thermal power plant, the inner and outer walls were operated in high-temperature steam and flue gas environments respectively. In this study, structure, microstructure and chemical composition of oxide films on inner and outer walls of ex-service low Cr ferritic steel G102 tube and ex-service high Cr ferritic steel T91 tube were analyzed. The oxide film was composed of outer oxide layer, inner oxide layer and internal oxidation zone. The outer oxide layer on the original surface of tube had a porous structure containing Fe oxides formed by diffusion and oxidation of Fe. More specially, the outer oxide layer formed in flue gas environment would mix with coal combustion products during the growth process. The inner oxide layer below the original surface of tube was made of Fe-Cr spinel. The internal oxidation zone was believed to be the precursor stage of inner oxide layer. The formation of internal oxidation zone was due to O diffusing along grain boundaries to form oxide. There were Fe-Cr-Si oxides discontinuously distributed along grain boundaries in the internal oxidation zone of G102, while there were Fe-Cr oxides continuously distributed along grain boundaries in that of T91.     

Combustion-Supporting Effect of Common Carbonous Solid Waste on Anthracites

In order to study the combustion characteristics of anthracite with additives, the influence of common carbonous solid waste (CSW) on anthracite is studied by thermogravimetry. The results show that appropriate CSW additives mixed with pulverized coal (PC) at PZH Steel can promote the combustion of PC and increase the burning ratio of anthracite greatly. The greater the additive content, the higher the burning ratio at the same conditions. The dynamics models show that the particle size of CSW additives, oxygen concentration, and the diffusion coefficient of oxygen are all very influential for their combustion characteristics. The heat of CSW combustion is absorbed by coal powder, and it consists of part of the coal powder accumulated heat. Then, accumulated heat is higher than dissipation heat ahead of time, so CSW can support combustion of coal powder effectively.     

水泥回转窑筒体裂纹形成原因分析

利用断口分析、光学金相、扫描电镜等手段,研究了回转窑简体裂纹性质和形成机理.     

Mathematical modelling and numerical optimization of particle heating process in copper flash furnace

A mathematical model of the particle heating process in the reaction shaft of flash smelting furnace was established and the calculation was performed. The results indicate that radiation plays a significant role in the heat transfer process within the first 0.6 m in the upper part of the reaction shaft, whilst the convection is dominant in the area below 0.6 m for the particle heating. In order to accelerate the particle ignition, it is necessary to enhance the convection, thus to speed up the particle heating. A high-speed preheated oxygen jet technology was then suggested to replace the nature gas combustion in the flash furnace, aiming to create a lateral disturbance in the gaseous phase around the particles, so as to achieve a slip velocity between the two phases and a high convective heat transfer coefficient. Numerical simulation was carried out for the cases with the high-speed oxygen jet and the normal nature gas burners. The results show that with the high-speed jet technology, particles are heated up more rapidly and ignited much earlier, especially within the area of the radial range of R=0.3–0.6 m. As a result, a more efficient smelting process can be achieved under the same operational condition.     

工艺气体消耗近于零的气体渗碳法

热处理炉,尤其是渗碳及淬火炉,都是连续不断地向炉内通入工艺气体。尽管工艺气体的消耗相当可观,也是热处理成本的一部分,但到目前为止,所通入的工艺气体都是通过废气口烧掉了。本文所述的技术是将工艺气体催化再生后,再送回热处理炉中,渗碳淬火炉的工艺气体消耗量可节省高达90％。本文重点介绍了新的再生技术的概念、实施以及工业应用的效果。     

Die Rolle der Begleitstoffe von Abgaskondensaten aus der Erdgasverbrennung bei der Korrosion von Wärmetauschern

Impurity constituents of flue gas condensates and their significance for the corrosion of heat exchangers This paper presents investigations concerning the acidic constituents of flue gas condensates which may be generated by the combustion of natural gas. Nature, origin and concentration of relevant constituents will be presented. Their corrosive impact on components of domestic heating facilities will be discussed taking into consideration usual materials based on aluminium, stainless steel and copper. It will be shown that condensates are considered as diluted and aerated acids with a moderately reduced pH. With respect to aluminium based alloys and stainless steels the corrosive potential of condensates is deduced from their content of strong acids. When condensing is forced due to techniques which are used in condensing boilers there is an effect of dilution active which results in a reduction of the corrosiveness. The primary corrosion mechanism of copper is related to the presence of oxygen in the condensate. Therefore the dilution of condensates is of restricted significance. Unprotected copper is known to be unsuitable for condensing conditions.