共查询到18条相似文献,搜索用时 906 毫秒
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加热炉是延迟焦化装置的关键设备,由于焦化的工艺特性加热炉炉管结焦是一个必然发生的现象,也是影响装置长周期运行的一个制约因素。主要分析了焦化加热炉炉管结焦的机理及影响因素,并提出了预防及减缓措施。 相似文献
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对原油直接式加热炉炉管失效实例进行了较为全面的理论分析,结合工业装置取样,通过宏观检查、化学分析、金相组织、腐蚀显微特征、X-ray衍射结构分析等方法,详细阐述了原油直接式加热炉炉管失效的机理,实验结果与理论分析的结论比较吻合。 相似文献
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Hong Bo Dinh Jong Min Yu Kee Bong Yoon Chul Park Sungwoo Ryu 《Journal of Mechanical Science and Technology》2018,32(12):5637-5645
When heat exchanger tubes have critical thinning which could cause unsafe conditions, it is general practice to plug the tubes so that they are out of service to prevent rupture failure at the thinnest location. Plugging criteria for the high-pressure feedwater heater tubes of fossil power plant were studied. Tubes in the desuperheating zone were considered due to their high internal pressure and the high temperature difference across the tube wall. Theoretical analysis of uniform thinning and eccentric thinning of the tube was conducted to determine the stress conditions at the thinnest location under internal/external pressure and thermal gradient across the tube. The minimum required tube thickness was determined using the maximum shear stress criterion (Tresca theory). Accuracy and effectiveness of the analytic solutions of the stresses were verified by comparing the results obtained with those obtained from finite element analysis. Using finite element analysis, the stresses for eccentric thinning were determined. Thermal loading due to temperature difference across the wall was considered even though the contribution of pressure loading to the stress of the tube was known to be higher than that of the thermal loading. As case studies, the tube plugging criteria of three high pressure feedwater heaters were determined using actual temperature and design pressure industry data. The procedure used in this study can be applied to different pressure and temperature operating conditions, and different tube materials. 相似文献
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基于蠕变损伤力学理论的HK40炉管焊接接头的蠕变损伤研究 总被引:2,自引:0,他引:2
1 前言熔焊技术的发明给制造业带来了革命性的变化 ,使得化工、石化以及发电等工业的大型高温过程装置得以建造。可是 ,在高温构件的失效中 ,焊缝的先行失效占有较大的比例 ,从而表明焊接对结构完整性的不利影响。为了实现高温构件的优化设计与维修 ,准确预测焊接构件的高温性能变得十分重要。转化炉炉管是高温下烃类转化制氢的关键部件。炉管材料一般采用离心铸造耐高温合金HK型( 0 4C ,2 5Cr,2 0Ni)或HP型 ( 0 4C ,2 5Cr,35Ni) ,整个炉管通常由 3~ 4根短管焊接而成。炉管在长期的高温服役过程中 ,材料微观组织劣化在晶… 相似文献
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总结了两年多来中国石化炉管质量检测检验与评估中心对乙烯裂解炉管抽样检测的状况。对国产乙烯裂解炉141根离心铸造炉管、24根炉管焊接件以及27根静态铸造管件开展了化学成分、室温拉伸性能、高温持久性能试验和低倍组织酸蚀试验,给出了当前国产离心铸造炉管行业对杂质元素含量的控制情况、国产离心铸造炉管和静态铸造管件的室温拉伸性能与高温持久寿命状况,以及柱状晶与等轴晶比例。结果表明,当前国产乙烯裂解炉管合格率在80%~90%左右,炉管焊接件和静态铸造管件的高温持久寿命基本不合格,凸显出了国产乙烯裂解炉管行业存在的严峻问题。还就离心铸造炉管和管件杂质元素、新制造炉管性能与服役炉管失效模式的关系等问题开展了讨论。 相似文献
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After having reviewed briefly the reliability of vacuum tubes on spacecraft, it is shown that the operation in space of a vacuum tube with an open structure is possible provided adequate measures are taken. The tube considered here is a multielectrode electron gun emitting electrons into space, in order to control the potential of a satellite. To avoid the failure of the most sensitive element of the gun, namely the impregnated tungsten cathode, the gun design includes such characteristics as a slow warming up of the heater element, a reactivation program used in case of cathode contamination, and a clean opening system which is not contaminant. Similarities with communication tubes are considered and the advantages of open tubes are mentioned. 相似文献
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模糊人工神经网络在真空管太阳能热水器热效率预测中的应用 总被引:2,自引:0,他引:2
热效率是设计真空管太阳能热水器时的重要参数。本文综合应用模糊数学和神经网络的知识构建了一个模糊神经网络模型。根据真空管太阳能热水器的真空管支数、真空管长度、集热面积、容水量等物性参数和初始水温、平均环境温度、辐照量和风速等环境参数,预测太阳能热水器的热效率。结果表明,该方法速度快,结果较准确,为真空管太阳能热水器的设计提供了一个新的辅助手段。 相似文献