Experimental investigation on the conversion of fuel-N to NOx of quasi-particle in flue gas recirculation sintering process

Flue gas recirculation sintering process is a potential technology to decrease fuel consumption and NOx emissions compared with conventional sintering process. In present work, a vertical quartz tube reactor was used to investigate the combustion characteristics and conversion of fuel-N to NOx of quasi-particle. The mass conversion rate of quasi-particle increases with higher temperature. It was found that D₁ model is more appropriate than other models to describe quasi-particle combustion process through comparing correlation coefficients calculated by different mechanism models. Effects of temperature, coke size and proportion, circulating flue gas components on the conversion of fuel-N to NOx of quasi-particle were studied. The conversion rate of fuel-N to NOx of quasi-particle increases with higher temperature. With increasing coke size and proportion, the conversion rate of fuel-N to NOx decreases obviously. O₂ has a positive impact on the conversion of fuel-N to NOx of quasi-particle. CO could decrease the conversion rate of fuel-N to NOx by reducing NO directly or reacting with char to decrease NOx indirectly. CO₂ has an obviously inhibitory effect on the conversion of fuel-N to NOx of quasi-particle because it reacts with char to generate CO. The results were conducive to further understanding the combustion behavior and NOx formation mechanism of quasi-particle during flue gas recirculation sintering.     

Failure analysis of R-regions of CFRP hat-shaped structure under pull-off load

Journal of Mechanical Science and Technology - As a kind of typical structure, the hat-shaped structure (HSS) is widely used in carbon fiber reinforced plastics (CFRP) aircraft parts. In this work,...     

溶聚丁苯在浅色鞋底胶中的应用研究

研究了溶聚丁苯(SSBR)在浅色鞋底胶中的应用情况,通过对胶料硫化特性、力学性能、耐磨性及防滑性能的测试及分析。试验结果表明,溶聚丁苯部分替代乳聚丁苯对浅色鞋底胶料的硫化特性、硬度、拉伸性能影响不大;随着溶聚丁苯用量的增加,胶料的撕裂强度、湿摩擦系数明显增加,而磨耗体积逐渐降低,可考虑将溶聚丁苯用于浅色鞋底胶料中,在改善胶料耐磨性的同时,提高胶料的防滑性能。     

130t/h燃气蒸汽锅炉的开发设计

介绍了130 t/h燃气蒸汽锅炉的关键技术及结构设计特点.经过实际运行验证,锅炉运行效率高、污染物排放低,满足国家环保指标要求,为用户创造了良好的经济和社会效益.     

星载SAR非沿迹成像新模式:机遇与挑战

星载合成孔径雷达(SAR)通过采用不同成像模式,实现分辨率与成像带宽度的不同性能组合。常规星载SAR模式的成像带沿着卫星航迹方向,走向单一;但实际目标场景的地理走向多种多样,与沿卫星航迹方向的成像带地理走向不匹配的情况普遍出现,导致数采周期长或方位分辨低、存储与计算资源浪费。星载SAR非沿迹成像模式是解决该问题的新思路,其通过生成与卫星航迹不同向的直线型或曲线型的成像带,匹配于目标场景的实际地理走向,对目标场景进行“地理定制化”成像。该文主要从信息获取、成像处理等方面,讨论了星载SAR非沿迹成像新模式的主要机遇与挑战,并通过计算机仿真实现了星载SAR非沿迹成像模式的原理性验证。      

不同温度下MoSi2的高温磨损行为研究

采用XP-5型高温摩擦磨损试验机考察了MoSi2/Al2O3配对副在700～1100℃间的摩擦学性能.利用扫描电子显微镜和X射线衍射仪观察与分析了MoSi2的磨损表面与相组成.结果表明:MoSi2/Al2O3摩擦副低于900℃时摩擦因数随温度升高而增加,MoSi2的磨损率较低,氧化与粘着磨损是MoSi2的主要磨损形式;高于900℃时摩擦因数略有下降,但基本维持在0.6～0.8之间, MoSi2的磨损率却显著增加,这是由于塑脆转变特性的影响,MoSi2磨损表面还发生磨粒磨损、变形与断裂,粘着和氧化磨损加剧;偶件Al2O3的磨损形式为粘着磨损.     

基于CNC的自适应直接分层制造方法研究

将RP技术的增材制造理念与数控铣削加工技术相结合,提出了基于CNC机床的金属零件分层制造方法。为解决等厚分层方法存在的缺陷,提出了基于相邻层面积变化比率和轮廓法向矢量的自适应直接分层算法,并在Pro/E软件平台上,利用Pro/TOOLKIT进行了系统的开发。该方法采用定厚板材作为造型材料,在等厚分层的基础上对分层板进行自适应分层切削,有利于保证成型精度和提高成型效率,为复杂形面功能零件的快速成型制造提供了一种有效的方法。     

Tool life evaluation of CFRP drilling with three kinds of drill

Serious tool wear in CFRP drilling is one of the key problems to be solved urgently. Firstly, a suitable indirect evaluation index of tool life is selected according to the literature. The critical delamination force was obtained by blind hole pushing experiment. Then, tool wear experiments were carried out with double point angle drill, stepped drill and reverse edge compound drill to analyze the variation rules of the thrust force, exit burr, exit delamination and tear with tool wear. Threshold values of exit delamination, tearing and critical thrust force were compared with each evaluation index one by one to study the causes of drills failure. The results indicated that the maximum tool wear position was the outer corner. Among the three types drills, the thrust force, delamination factor and burr angle of the reverse edge compound drill are smaller. The double point angle drill fails due to the excessive thrust force, while the stepped drill and the reverse edge compound drill fail due to the hole exit delamination exceeding the threshold. The number of drilled holes of the reverse edge compound drill is 100 % and 25 % higher than that of the double point angle drill and the stepped drill, respectively. Therefore, the reverse edge compound drill is suitable for drilling CFRP.

     

基于CT显微图像的烧结矿孔隙特征分析及有效热导率预测

全面了解获取多孔烧结矿的热物理特性对于在钢铁企业中相关过程的运行优化和节能减排具有重要意义。在此前景下,无损的高精度X射线显微断层扫描技术被应用到表征烧结矿的孔隙结构并结合数值模拟来预测烧结矿的有效热导率。以40 μm的分辨率扫描了3个熟石灰添加水平下的烧结杯试验中获取的烧结矿样品。三维重建后的烧结矿可观测到各向异性的非常复杂的孔隙分布,导致其有效热导率也各向差异较大,形成复杂的内部温度场分布。烧结矿中0～300 μm的小孔隙在数量频率上占据大多数（约45%～50%）,但仅占小部分的大于1 mm的大孔隙则贡献了约95%的孔隙体积占比,并主要决定了烧结矿的导热行为。3个烧结矿样品的有效热导率分别为0.645、0.682和0.784 W·m^-1·K^-1,对应的孔隙率分别为53.8%、53.1%和49.7%。通过与文献中的类似铁系聚合物的导热值,典型的经验式预测方程和结构分析模型等比较,证明了CT三维重建结合数值模拟的技术手段可有效捕捉烧结矿真实的多孔结构,从而比简单的经验式方程或结构分析模型能获取更精确的热物理行为的预测效果。