Heat exchanger is a universal process equipment, which is widely used in chemical industry, oil refining, thermal power and other industries. Shell-and-tube heat exchangers often fail prematurely due to flow-induced vibration. In this paper, aiming at the problem of severe vibration of shell-and-tube heat exchanger in an enterprise, the vibration acceleration sensors are used to measure the vibration of shell and tube side of heat exchanger. Through the analysis of the measurement results, it is found that when the flow rate on the shell side of the heat exchanger is greater than 50000 Nm3/h, the flow-induced vibration of the tube bundle occurs, and the vibration frequency is 57Hz, which is close to the natural frequency of the tube bundle. And the greater the flow rate on the shell side, the more intense the vibration. In order to reduce the vibration of heat exchanger, the damping measure of inserting baffles between tubes is adopted.
P91 steel is widely used in high temperature components of ultra supercritical thermal power units, whose high steam parameters can improve the thermal efficiency. Creep cavities can be used to evaluated the creep damage state of the P91 power plant steel. In this study, industrial computed tomography (CT) tests were conducted on the crept P91 steel sample. It was found that the digital radiography (DR) and CT images using 12 W target power exhibited clearer internal defect morphology than that of the images taken with 80 W target power, because the relatively low target power kept the focal spot small. In addition, combined the CT images along radial and axial directions, the creep cavities of P91 steel were judged as long strip volume defects with ~50 μm diameter along the stress direction, demonstrating that the industrial CT testing method could be applied to defect detection of other power plant materials.
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