一种基于壅塞原理的多路气粉两相流等流量控制方法

在诸如高炉喷吹煤粉等粉状物料气力输送的场合,常有将粉料经过多条不同长度和布置的路径,按相同的质量流量连续输送到多个目的地的工艺要求.本研究将纯气流的壅塞现象推广到气粉两相流中,对基于气粉两相流壅塞原理的多路气粉两相流等流量控制方法进行了实验验证.实验结果表明,若在各支管路入口之前加入一组具有相同尺寸的壅塞喷管,并满足相应的压力条件时,可使流过各壅塞喷管的多路气粉两相流的速度在其喉口处同时达到音速,且该速度不会因后续管路的长短和布置而改变,进而可以起到均衡流经各支管路的气粉两相流质量流量的作用.通过对发生壅塞现象时,煤粉的质量流量和进口压强的关系以及临界压强比等参数的实验确定,给出了壅塞喷管的选择依据和使用条件.     

竖炉生产直接还原铁过程的数值模拟

采用基于气相和固相的质量和能量的竖炉一球团（块矿）法直接还原炼铁的一维数学模型．含铁原料的还原采用三界面未反应核模型,并考虑了热量损失,得到了各物质的组成和温度在炉内的分布．以Gilmore厂Midrex作为对象进行模拟,模型结果与生产数据相符,验证了模型的准确性．模拟结果表明：Midrex竖炉的绝大部分区域内气利和固相的温度基本保持在还原煤气的入口温度．对高度为9．75m的Midrex竖炉,炉内绝大部分为浮氏体的还原,含铁原料运行约0．5m即可完全变成磁铁矿,运行约2m即可完全变成浮氏体．在竖炉7．0～9．75m深度范围内,随着还原气的上行,H2的体积分数迅速减少,而CO的体积分数变化不大．在竖炉2．0—7．0m深度范围内,H2和CO的体积分数缓慢降低,在竖炉0～2．0m深度范围内,H2和CO的体积分数显著降低．     

Preparation and Structure of Mg2-xRExNi （RE = La, Ce, Pr, Nd, Y） Ternary Alloys

A series of Mg2-xNdxNi (x =0.05, 0.1, 0.2, 0.3) alloys and Mg1.95RE0.05Ni (RE= La, Ce, Pr, Nd, Y)ternary alloys were prepared by ball milling of mixted powder of Mg, Ni, RE and sintering under the protection of argon. XRD analysis shows that Mg2-xNdxNi (x = 0.05, 0.1 ) and Mg1.95RE0.05Ni consist of single phase with the same crystal structure as Mg2Ni. While three-phase alloys including Mg2Ni, NdNi and NdMgNi4 were formed in Mg1.8Nd0.2Ni and Mg1.7Nd0.3Ni alloys respectively. The lattice constants of Mg2Ni in those ternary alloys were calculated. The decomposition of Mg2Ni occurs in the milling process of Mg2Ni and Mg1.95RE0.05Ni alloys respectively. For the latter, another earlier reaction occurs in milling process, which means that atoms of RE are separated from crystal structure of Mg2Ni and form relevant oxides by combination with oxygen existed in argon atmosphere.     

基于煤气化学能最大化利用的上部吹氧竖炉静态模型

针对竖炉生产中存在的煤气还原势未能充分利用、煤气消耗量高以及二氧化碳排放高等问题,设计出一种上部增设吹氧装置的竖炉.基于物料平衡和热平衡建立了上部吹氧竖炉的静态模型,并对其进行了数值求解模拟和分析.模拟结果表明,在典型条件下,上部吹氧竖炉每吨直接还原铁的还原煤气量为1404.67m³,吹氧量为20.32m³,煤气出口还原势降至0.56,排碳量减少26.25%,能耗减少19.56%.     

圆筒型冶金反应器内非轴对称流动的数值模拟

用新开发的同位网格适体坐标程序来描述圆筒型冶金反应器内非轴对称流动,从而回避了柱坐标下极点奇异性问题.数值模拟结果与实验结果对比表明:新开发的程序是可靠的,用该程序对单点偏心底吹氩气搅拌钢包炉(LF)的喷嘴位置进行优化,结果表明:当喷嘴布置在r/R=0.333处时,LF内钢液流动结构最合理,这与实际生产是相符的.     

基于新变量选择方法的FNN预报转炉终点

考虑到机理模型能较准确给出转炉吹炼过程的定性规律，而难以给出可靠的定量关系，首先利用冶金机理模型和PLS方法分析影响转炉终点碳的因素，然后建立基于模糊推理神经网络的转炉终点碳预报模型。结果表明，此法能有效提高对转炉终点碳预报的命中率和网络的训练速度。在w(C)绝对误差±0.02%控制精度下命中率达94.12%，相对误差±10%控制精度下命中率达56.86%。     

振动形成的单一尺寸硬球晶的结构表征及其动力学的离散元模拟

采用离散元(DEM)数值方法结合物理实验,分别实现了单一尺寸硬球在三维(3D)间歇振动及批量加料条件下堆积的有序化(结晶),通过对晶体的结构表征、数值仿真中的微观性能如配位数(CN)、径向分布函数(RDF)、角分布函数(ADF)、Voronoi/Delaunay孔的尺寸分布、力的网络分析以及晶体形成过程中的动力学分析,...     

流化床反应器的流动模型

在理论分析的基础上,建立了流化床反应器的流动模型,给出了气体流速、床体尺寸、处理能力等参数的计算公式和判断内部流态化流型的依据。在此基础上,给出了1个模型的算例,并与文献给出的计算结果相比较,结果表明二者的符合性较好,根据模型计算得到的参数具有良好的合理性。该模型对使用流化床反应器炼铁有一定的指导意义。     

水平气体分布器对COREX C3000竖炉内气体流场的影响

通过建立三维数学模型解析COREX C3000预还原竖炉内煤气流分布情况,分析水平气体分布器(HGD)对煤气流的影响.结果表明,HGD增加了还原煤气进入竖炉时与炉料的接触面积,竖炉整体压差显著降低.安装HGD后,竖炉围管水平面的煤气流速增大,但对竖炉上部煤气速度的影响很小,且下部煤气死区体积变大.HGD可将煤气很好地引到竖炉中心,并对煤气反窜有良好的抑制效果,加装HGD后,反窜煤气的体积分数由12.23%降至8.29%.     

Preparation and tribological performance of electrodeposited Ni-TiB2-Dy2O3 composite coatings

TiB2 and Dy2O3 were used as codeposited particles in the preparation of Ni-TiB2-Dy2O3 composite coatings to improve its per-formance. Ni-TiB2-Dy2O3 composite coatings were prepared by electrodeposition method with a nickel cetyltrimethylanunonium bromide and hexadecylpyridinium bromide solution containing TiB2 and Dy2O3 particles. The content of codeposited TiB2 and Dy2O3 in the compos-ite coatings was controlled by adding TiB2 and Dy2O3 particles of different concentrations into the solution, respectively. The effects of TiB2 and Dy2O3 content on microhardness, wear mass loss and friction coefficients of composite coatings were investigated. The composite coat-ings were characterized by X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES) and scanning electron microscopy (SEM) techniques. Ni-TiB2-Dy2O3 composite coatings showed higher microhardness, lower wear mass loss and friction coefficient compared with those of the pure Ni coating and Ni-TiB2 composite coatings. The wear mass loss of Ni-TiB2-Dy2O3 composite coatings was 9 and 1.57 times lower than that of the pure Ni coating and Ni-TiB2 composite coatings, respectively. The friction coefficient of pure Ni coating, Ni-TiB2 and Ni-TiB2-Dy2O3 composite coatings were 0.723, 0.815 and 0.619, respectively. Ni-TiB2-Dy2O3 composite coat-ings displayed the least friction coefficient among the three coatings. DY2O3 particles in composite coatings might serve as a solid lubricant between contact surfaces to decrease the friction coefficient and abate the wear of the composite coatings. The loading-bearing capacity and the wear-reducing effect of the Dy2O3 particles were closely related to the content of Dy2O3 particles in the composite coatings.