换热器试运行期间管束焊缝发生疲劳断裂分析

采用金相、扫描电镜方法对304L不锈钢换热管试运行期间的焊缝开裂进行了分析。宏观分析和微观分析表明管子与管板连接的焊缝断裂是疲劳破坏所致。流体诱导导致的管束共振是换热管短期失效的主要原因,胀接不合格、焊接缺陷加速了管束的疲劳失效。

黔西电厂3号高压加热器振动原因排查

贵州黔西电厂1号机组在启动运行过程中。负荷超过250MW时3号高压加热器及其附近楼板和给水管道发生国内外罕见的振动。分析后认为这些振动源自3号高压加热器．3号高压加热器振动由管束共振引起。共振的激振力来自VHB／3—125T3型给水三通阀。一年后，对3号机组的给水三通阀进行内部改造。振动消除。本文侧重介绍振动原因的排查过程．并介绍了可供工程设计与建设参考的若干体会。

Acoustic Resonance in Exhaust Gas Economizer Tube Bundles Prediction and Suppression of Resonance

The tendency for air column resonance generation in structures with a constant volume behind a tube array like that of an exhaust gas economizer has been reported, but many points remain unclear with respect to the mechanism and conditions that generate acoustical resonance. When acoustical resonance is generated, in reality, prevention and suppression measures are implemented by inserting a baffle plate into the ducts through a process of trial and error. The purpose of this study is to clarify the mechanism of generation of acoustical resonance, and to establish an appropriate measure to prevent such resonance. Noise generated in an exhaust gas economizer was correlated with the flow inside the tube array and experimentally analyzed, and the mechanism for resonance generation was considered. In addition, the effectiveness of a baffle plate positioned in order to prevent resonance was investigated. We have successfully employed a single baffle plate to suppress resonance.

MRI诊断前列腺癌侵犯神经血管束的价值

目的观察前列腺癌侵犯神经血管束患者通过磁共振成像MRI进行临床诊断具体意义.方法：选取我院自2013年10月至2014年6月收治的前列腺癌症患者症状：排尿困难、尿失禁、血尿等;肛肠指诊前列腺肿大,并触及质硬、外突结节54例,进行术前MRI诊断扫描,并于前列腺切除术后进行外科病理检查,对比两种诊断方法对于前列腺癌侵犯神经血管束情况的诊断进行比较,并判断MRI这种诊断方式对于前列腺分期诊断的准确性、特异性、敏感度.结果：MRI检查可见：54例前列腺癌患者中,有45例诊断为神经血管束侵犯,其中：表现为T1WI：1.前列腺后外侧局限性突出,未见神经血管束显示;2.神经血管束局限性增粗;3.前列腺后外侧及神经血管束间脂肪间隙消失.MRI检查结果与病理检查结果一致其总体准确度为83.33%;具有统计学意义（P〈0.05）.结论：磁共振成像（MRI）对于前列腺癌患者,作为术前确诊患者癌症分型及侵犯具体部位来说,是明显优于其它诊断方式的,是术前必备的诊断方法,值得临床推广使用.