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.
Cross-flow induced vibrations in a tube bank—Vortex shedding
Abstract An experimental wind-tunnel facility which was developed specifically to study cross-flow induced vibrations in heat exchanger tube banks is described. Nineteen tubes in the centre of the closely packed array were flexibly mounted in order that their response and interaction with the flow could be studied. The surrounding 116 tubes were fixed and could be easily removed to study the effect of tube bundle size on flow phenomena and tube response. Results are presented in this paper for vortex shedding while those for turbulent buffeting and fluid elastic instability will be presented in the sequel to this paper.
Fault Diagnosis and Analysis of Rotor Imbalance of Rotating Machinery
The rotor imbalance fault of rotating machinery is caused by the quality eccentricity or bugs of rotor components.Nearly seventy percent of rotating machinery fault is related to the rotor imbalance.In addition,there are various and similar rotor faults.Thus,it is very necessary to study and analyze the rotor imbalance fault,as well as discriminate fault types of rotating machinery.