This research aims to develop a method to evaluate the deterioration of the tube material within a boiler, in order to reduce the failure of it. In this thesis, natural frequency measurement method and ultrasonic attenuation method are mainly applied, and it has reached to a conclusion that the ultrasonic attenuation method is more reliable.
Traditionally, the inspectors used the ultrasonic thickness measurement machine to evaluate the thickness and track the condition of a boiler. However, besides the thickness, the inspectors could not have clear understanding of the material and situation within a boiler. To improve the inspection effectiveness, the researcher measures the natural frequencies of the tube material in the new and old boilers by using natural frequency measurement. They found that the used tube material has been altered due to the difference between the natural frequencies.
The ultrasonic attenuation conditions of the tubes are also evaluated in this thesis. The echoes of the ultrasound propagating through the thickness of the tube can be analyzed by relative comparison and absolute comparison, respectively. The relative comparison compares the echoes of the multiple back reflections of the ultrasound between the tubes of old and new boilers. In addition, the absolute comparison analyzes the amplitude of the echoes of the ultrasonic multiple back reflection to calculate the ultrasonic attenuation of the tube. Besides the two major techniques, the material analysis, metallurgical analysis, internally scale analysis and mechanical property evaluation are also applied in this thesis to help developing a method to evaluate the deterioration of the tube material within a boiler.
This research demonstrates that the ultrasonic attenuation measuring methods can offer reliable results to evaluate the quality of the boiler.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0809105-163616 |
| Date | 09 August 2005 |
| Creators | Wang, Ping-Chih |
| Contributors | Shao-Yi Hsia, Yi-Cheng Huang, Jin-Jhy Jeng, Shiuh-Kuang Yang |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0809105-163616 |
| Rights | not_available, Copyright information available at source archive |
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