不锈钢换热器管束断裂原因初探

对抚顺石油二厂石蜡加氢装置热高分气冷却器E-3A不锈钢U形管束周向开裂的原因进行了初步探讨,从管束的选材、制造、使用、开裂管子外观检查、金相检验、断口分析、腐蚀产物分析几方面得出结论:不锈钢U形管周向开裂是由于在含有氧化物的高温水和水蒸气的腐蚀介质中引起应力腐蚀破裂,直接原因是管束选用的1Cr18Ni9Ti碳含量偏高,且整体热处理工艺严重失误共同造成严重的晶间腐蚀。对防止应力腐蚀开裂提出了相应的措施。     

玻璃纤维硅砂增强管结构在涵洞中的试验研究

该项目完成了玻璃纤维硅砂增强管结构在公路涵洞中的试验。通过静载试验,对涵管的竖向变形、最大挠度、裂缝开展情况、涵管整体沉降等进行了实测与分析,得出了一些结论,可为玻璃纤维硅砂增强管结构在公路涵洞的推广应用提供一些参考依据。     

Experimental investigation of the stiffness of critical components in a moment-resisting composite connection

This paper discusses results of experiments on an element of a proposed moment-resisting composite connection. The element is subjected to cyclic tension. A feature of this element is the use of blind bolts and extensions to these bolts into the concrete-filled CHS column. The test specimens with extensions failed at a higher load and showed increased initial stiffness compared to the specimen without extensions. The experimentally derived values of initial stiffness are also compared to the initial stiffness values derived from a mechanical component model of the connection element.     

石家庄热电厂尖峰炉过热器管裂纹分析

针对石家庄热电厂尖峰炉多根过热器管下弯头开裂泄漏的现象,进行了宏观分析、金属化学成分分析、金相试验、力学试验、SEM电镜分析、管内垢样分析等试验,确定了过热器下弯头处的泄漏为苛性脆化,并分析了脆性破坏的发展过程。     

电缆输送过油管射孔工艺技术在玉门油田的应用

针对青西油田老井侧钻、加深及部分深井小井眼完井不能采用常规射孔器射孔现状,选用无枪身射孔工艺,解决了完井难题,探索出一套无枪身射孔器射孔的施工方法,提高了施工井的成功率,为今后实施该项工艺积累了经验。     

油管疲劳累积损伤的磁记忆检测

研究了油管的破坏形式及磁记忆检测方法，使用应力集中磁指示仪对油管螺纹和周向裂纹进行了检测和数据分析。结果表明，磁记忆是检测油管缺陷和应力集中程度的有效方法。得出了油井中应重点检测靠近井口的1～10和80～90根油管，给出了油管上的重点检测部位。     

槽筒数字化设计与制造方法的研究及应用

槽筒是自动络筒机上用于卷绕成形的关键零件.该薄壁回转体上的导纱线槽形状复杂,制造要求高.开展数字化槽筒设计与制造方法的研究和实践,是实现高档次络筒机国际竞争力的主要途径之一.文章就槽筒导线槽设计、加工工艺、定位夹紧方案及数控编程进行了研究和实践,取得了较为理想的效果.     

Thermoeconomic optimization for a finned‐tube evaporator configuration of a roof‐top bus air‐conditioning system

This paper presents a methodology of a design optimization technique that can be useful in assessing the best configuration of a finned‐tube evaporator, using a thermoeconomic approach. The assessment has been carried out on a direct expansion finned‐tube evaporator of a vapor compression cycle for a roof‐top bus air‐conditioning (AC) system at a specified cooling capacity. The methodology has been conducted by studying the effect of some operational and geometrical design parameters for the evaporator on the entire cycle exergy destruction or irreversibility, AC system coefficient of performance (COP), and total annual cost. The heat exchangers for the bus AC system are featured by a very compact frontal area due to the stringent space limitations and structure standard for the system installation. Therefore, the current study also takes in its account the effect of the variation of the design parameters on the evaporator frontal area. The irreversibility due to heat transfer across the stream‐to‐stream temperature difference and due to frictional pressure drops is calculated as a function of the design parameters. A cost function is introduced, defined as the sum of two contributions, the investment expense of the evaporator material and the system compressor, and the operational expense of AC system that is usually driven by an auxiliary engine or coupled with the main bus engine. The optimal trade‐off between investment and operating cost is, therefore, investigated. A numerical example is discussed, in which a comparison between the commercial evaporator design and optimal design configuration has been presented in terms of the system COP and evaporator material cost. The results show that a significant improvement can be obtained for the optimal evaporator design compared with that of the commercial finned‐tube evaporator that is designed based on the conventional values of the design parameters. Copyright © 2007 John Wiley & Sons, Ltd.     

Heat transfer enhancement in a tube using circular cross sectional rings separated from wall

A numerical study was undertaken for investigating the heat transfer enhancement in a tube with the circular cross sectional rings. The rings were inserted near the tube wall. Five different spacings between the rings were considered as p = d/2, p = d, p = 3d/2, p = 2d and p = 3d. Uniform heat flux was applied to the external surface of the tube and air was selected as working fluid. Numerical calculations were performed with FLUENT 6.1.22 code, in the range of Reynolds number 4475–43725. The results obtained from a smooth tube were compared with those from the studies in literature in order to validate the numerical method. Consequently, the variation of Nusselt number, friction factor and overall enhancement ratios for the tube with rings were presented and the best overall enhancement of 18% was achieved for Re = 15,600 for which the spacing between the rings is 3d.     

顶镦压力曲研究

锅炉蛇形管小R制造中,先将管子预弯到1.5倍D半径,然后再挤压到1倍D半径。但数控顶镦弯管机可以直接弯制1倍D半径管子。