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.
Research of Amplitude-Frequency Domain Parameters Analysis for Condition Detection and Fault Diagnosis
According to incomplete statistic, about 30% of the machinery fault is caused by the rotating component. But, the rotating machinery vibration testing and fault diagnosis has the problems of collecting useful information containing the noise, etc. So, this study adopted the time-frequency analysis technology to realize the rotating machine condition test and fault diagnosis. The actual rotation machinery vibration data after pretreated is used to identify the work conditions of the rotating machinery equipment through analyzing the parameters of the time domain and frequency domain, which accurately judge the rotating machinery equipment fault condition. After finding the fault starting time by using the time domain parameters, the frequency spectrum analysis is used to grasp the fault type by comparing the vibration signal character of the energy frequency spectrum. Through the simulation we can see, time domain parameters can judge the rotating machinery equipment fault occurs time accurately and exactly find the fault type by the frequency spectrum energy.
CMEOC—An expert system in the coal mining industry
Abstract This paper introduces an expert system in the mining industry, called the Coal Mining Expert and Optimization Consultation System (CMEOC). The paper mainly describes the architecture of this system, including the knowledge base, inference engine, and relevant optimization techniques. The techniques include multi-objective programming, fuzzy sets, and integer programming. The application results present evidence of the usefulness of the system.