Research On Detection And Diagnosis System Of Boiler Tubes Leakage Based On Chaos And Fractal Theories

The troubles of boiler tube leak have become the key problem on the machine safe stable movement in our country. Based on the present domestic and international actualities, this paper makes in-depth experiments for the technology of boiler tube leak detection and diagnosis, and develops the system of the boiler tube leak detection and diagnosis. These are the main contents:The characters in time domain and frequency domain of the background noise inside boiler are analyzed theoretically and studied by experiments, and the upper limit frequency of it is confirmed, these are very important to the diagnosis of boiler tube leak and avoid wrong alarms.The computing formula that shows the relationship between r and the fractal dimension D is brought forward, supplies the theoretic foundation to the calculational methods of r. and the same conclusion is made through different diagnosis experiments by from the distributions of the maximum Lyapunov exponent to The Box-Counting dimension.It testifies that chaos is existed in the sonic signal of boiler tube leak, according to The Chaos Theory and the correlative contents about The Sky Dynamics, and illustrates the physical meanings of the Lyapunov exponent (the change at the place of the boiler tube leak), based on the calculational methods of the Lyapunov exponent and the peculiarities of boiler tube leak detection and diagnosis.The " expanding in frequency domain" theory is put forward and validated, and the chaos theory and the fractal theory is applied to the detection and diagnosis of boiler tube leak, the separation between the useful signal and noise and some of problems existed in the present boiler tube leak detection are solved.The "expanding in frequency domain" theory that makes the fractal theory and the chaos theory more advantageous is fit for normal analysis in time domain. Adopting the "expand in frequency domain" theory, not the linear prediction in phase space reconstruction algorithms, the reductive computing of boiler tube leak signal is done and validated by experiments. The one dimension Lyapunov exponent mode of boiler tube leak prediction is confirmed.In-depth experiments are made for all kinds of the boiler tubes leak and diagnosis. The main experiments: the relationship between the sonic intensity and the pressure of the steam that leak out of the boiler; the relationship between the level of the intensity of the leak noise and the capability of boiler; the effect that wave-guide tube has on the detection of leak noise; the specialties of sonic intensity level of background noise and distributing in frequency.Based on the analysis and summarization about the hardware and the diagnosis theories of the no. 1 and no. 2 boiler tube leak monitor and diagnosis system, the design optimization is studied, and the experiments and theories about boiler tube leak detection and diagnosis are realized through the chaos and fractal theory; the develops and designs of boiler tube leak detection and diagnosis system are finished, and acquire some good benefits.