A case study: Monitoring heat exchanger based on vibration sensors and nondestructive testing technique
Flow-induced tube vibration could cause serious damage on large-scale circulating-water heat exchanger in factories, e.g., atomic reactors, nuclear power plants, petroleum and chemical industry. Therefore, efficient inspection technology is very important for heat exchanger's blockage and leakage. The existing detection technologies, like temperature test and pressure test, are very easily affected by extraneous factors, e.g., temperature and pressure, while the nondestructive testing technology based on vibration sensors is free from above limits. In this paper, we use vibration sensors to detect blockage and leakage of the circulating-water heat exchanger. According to the experimental results, it is found that when detecting heat exchanger's blockage and leakage with vibration sensors, environmental vibration from the working machines has influence upon the result, while pump vibration and vibration produced by liquid flowing through regulating-valve make little difference. Nevertheless, fault diagnosis of large-scale circulating-water heat exchanger, which uses nondestructive testing technology based on vibration sensors, needs to be further improved.
Virtual Instrument System for Rolling Bearing Failure Diagnosis
Aiming at that the bearing vibration measure instrument in our country can't indentify the abmomal sounds of the bearing, the new instrument system has been designed for bearing failure diagnosis. The system not only has functions, which hold by various bearing vibration instruments at present, but also has other functions. The relation of noise and vibration and design scheme of the instrument system are introduced. The practical example of the system is given. The results show that this system has high practical value and applicable foreground.
Experimental development of design criteria to limit liquid cross-flow-induced vibration in nuclear reactor heat exchange equipment
An extensive series of experimental vibration tests has been conducted on tube bundles of contemporary interest in a large water tunnel. The main objective of these tests has been to develop a design criterion to limit vibration amplitudes. It has been found that the main excitation mechanisms are turbulence, some vortex shedding, and hydroelastic instability. The results of these tests are correlated and presented. It is found that the most serious excitation mechanism is hydroelastic instability. Criteria are advanced for establishing upper velocity limits based on the experimental findings. The vortex shedding mechanism is found to only be a problem for tubes in the inlet region of some bundles. Strouhal numbers associated with observed resonances are tabulated and discussed. Tube response to random turbulence has been studied for numerous bundles but is found to be of secondary significance.