ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Modern waste burners are equipped with catalysts to reduce NOX. During operation the catalysts and their performance are influenced by, for example rapid temperature changes, facility vibrations, cleaning procedures and unwashed exhaust gas (when the catalyst is installed before the washer). The catalyst discussed in this paper comprised over 2’500 extruded elements of 150 x 150 x 770 mm3. During commissioning the catalyst elements exhibited a tendency to spall off pieces, thus preventing acceptance of the plant. For the failure analysis, one element from the catalyst was removed and two spare elements were selected. The investigation comprised a visual check, fractography, measurement of the most important physical, mechanical and chemical properties, and a microstructural analysis. It could be shown that:− Processing defects, such as extrusion defects, were the source of cracks which led to pieces spalling off;− Hot steam, used for periodic cleaning, reduced the structural strength by half;− The elements were exposed to higher mechanical loads than expected during transport;− The cleaning process, in combination with particles transported by the exhaust gas, has an erosive effect on the catalyst material;− Blockages, caused by catalyst material among other things, could be found at different depths;− The chemical composition did not significantly differ between used and unused elements.In summary, the failure analysis led to an understanding of the failure mechanism and to a set of recommendations for improvements whose implementation ultimately led to the plant being cleared for operation
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/49/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.290.78.pdf
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