Flow and Heat Transfer Phenomena around an Equilateral Triangular Bluff Body: Effect of Wall Confinement

This paper focuses on the effects of wall confinements (or blockage ratios) on the flow and heat transfer characteristics around a long equilateral triangular bluff body placed in a horizontal channel for Reynolds number (Re) range 1 to 80 and blockage ratio range 0.1 to 0.5 for air as the working fluid. The governing continuity, Navier–Stokes and energy equations along with appropriate boundary conditions are solved by using a finite volume method‐based commercial solver Ansys Fluent. The total drag coefficient decreases with an increasing value of Re for a fixed value of the blockage ratio; however, it increases with an increasing value of the blockage ratio for a fixed value of Re due to the fact that the channel walls exert an extra retardation force on the obstacle. The onset of flow separation is delayed as the value of the blockage ratio increases. The critical Re (i.e., the transition to a time‐periodic regime) exists between 45 and 46, 46 and 47, 58 and 59, and 79 and 80 for the blockage ratios of 0.1, 0.125, 0.25, and 0.5, respectively. The simple correlations for wake length, total drag coefficient, and average obstacle Nusselt number are obtained for the range of conditions covered.     

火电厂SCR脱硝系统氨管道污堵治理及优化控制

火电厂选择性催化还原(SCR)烟气脱硝氨系统出现故障,将影响到整个脱硝系统的运行安全。在理论分析的基础上,根据脱硝系统设备维护过程中氨系统污堵治理经历,总结出有针对性的治理措施及控制策略,主要包括:从源头控制液氨品质,在适当位置增加滤网,避免金属腐蚀,临时吹扫蒸发槽,喷氨流量计增加旁路,蒸发槽供氨管道、阀门保温与加热,加强定期检修和维护,完善调节阀控制逻辑等。实践表明,所采取的措施行之有效,避免了问题的再次发生。     

Formation and evolution of macro inclusions in IF steels during continuous casting

The evolution of macro inclusions during continuous casting was investigated by large-area inclusion characterization using ASPEX and analysis of nozzle blockage deposits. Six kinds of inclusions over 5?μm were observed in samples taken from the tundish and the slabs: single alumina particles, alumina dendrites, refractory-related alumina, alumina associated with bubbles, alumina clusters and Al–Ti complex oxides. By examining the morphology of the nozzle blockage deposit, it was concluded that the refractory-related alumina in the slabs came from the decarburization layer washed away by the steel stream. Some of the alumina clusters that came from the nozzle blockage deposit dislodged by the steel flow, were formed by the agglomeration and sintering of 5–20?μm inclusions that were carried over from the tundish. Two kinds of Al–Ti oxides were found in the tundish, and their evolution mechanisms during the casting process were proposed.     

锰烟尘储仓堵塞问题的解决

分析了烟尘储仓频繁堵塞的原因。在储仓圆锥体安装了多个空气炮喷嘴,利用压缩空气的膨胀力很好地解决了堵塞问题。     

Physical modelling investigation of influence of strand blockage on RTD characteristics in a multistrand tundish

Abstract

In the continuous casting process, the tundish acts as a continuous molten steel distribution vessel. The importance of the tundish during the molten steel delivery becomes more significant when it supplies liquid steel to more than one mould. In the present work, a water model of a six strand billet caster tundish has been used to study the effect of strand blockage on the residence time distribution (RTD) characteristics at the strands. All the experiments were performed under steady state conditions. Potassium chloride was used as a tracer for the study. The effects of blockage on the strand dissimilarity among the open strands were also studied. Both single and dual strand blockage experiments were performed. Blockage of strands deteriorated the RTD characteristics at the open strands. The results reveal the most preferred options for strand blockage when the plant operation needs to do so.     

露天坑底爆破飞石运动轨迹的理论分析及堵塞防护试验研究

通过理论分析,得出某露天采场坑底爆破时爆破飞石的运动轨迹及飞石飞行距离.结论表明,该矿爆破飞石对周边居民几乎没有影响.通过进一步的堵塞防护试验研究表明,砂袋覆盖炮孔口的防护措施对于改善爆破效果和减少爆破飞石具有重要作用.     

液动锤钻进减轻岩心堵塞机理的研究

通过对液动锤取心钻进过程中钻具的受力分析,论述了液动锤减轻岩心堵塞的作用机理,阐明了液动锤钻进技术的适用地层范围,介绍了其在汶川地震断裂带科学钻探工程WFSD-4号孔中应用取得的成果。     

提高单井产量技术研究与应用

尽管前期通过科研攻关,解决了一部分因地层堵塞、出砂、管外窜槽、油层物性差等原因造成的单井产量低下的工艺技术难题。但对于侧钻井出砂、长井段／薄互层直井分层压裂分段级数低、直井物理解堵技术无法实现选层等影响单井产量的问题尚未解决。针对上述技术瓶颈,开展小井眼地层深部防砂技术、连续油管压裂技术和选层负压解堵技术的攻关与研究工作,形成了新型树脂砂、连续油管跨式双封管柱和选层负压解堵工艺三项技术突破。其中,小井眼地层深部防砂技术实现了地层深部防砂技术在侧钻井上的应用,解决了小井眼钻树脂砂塞困难的问题;连续油管分层压裂技术不仅可以实现不动管柱进行2层或3层分层压裂施工,还可以用于2层或3层分层酸化作业施工;选层负压解堵技术将化学暂堵、机械解堵有机融合为一体．完成选层负压解堵工艺,从而达到最佳的解堵效果。这些技术的研制成功和现场应用,为油田稳产提供了技术保障。     

甲醇制丙烯工艺C_2循环系统的优化改造

针对甲醇制丙烯装置C2循环系统经常发生堵塞的现象,进行了原因分析,并通过提高CO2洗涤塔塔顶物料冷却温度和将部分脱乙烷塔塔顶物料旁通于干燥系统循环回反应器,解决了C2系统堵塞问题,保障了甲醇制丙烯系统的安稳运行。     

气力输送工业应用现状

气力输送在高效工业生产中有着举足轻重的作用,为高效工业生产奠定了坚实的基础。气力输送的形式多样、结构灵活,有着广泛的适应性。在实际的生产中气力输送系统中存在着一定的问题,特别是输送管线的堵塞,对此文章对该问题进行了一定的分析并给出一些应对方案。随着新技术、新材料的引入,气力输送系统的可靠性有所提高。