Possible improvements to the back-pulse cleaning of ceramic candle filters
Conference
·
OSTI ID:245014
- RWTH, Aachen (Germany). Lehrstuhl fuer Waermeuebertragung und Klimatechnik
For the successful application of hot gas filters with ceramic filter elements in coal fired power generation processes a stable cleaning of the filter elements must be guaranteed. The most frequent strategy of cleaning candle filters is back-pulse cleaning. To optimize the cleaning event a profound understanding of the physical phenomena involved in the build-up and break up of dust cakes is necessary. To determine the cohesive forces in a filter cake the strength of flat filter cakes was tested, by measuring the pressure difference driving the reversed gas flow through the filter that causes cake failure. Based on a model by Rumpf the measured strength of filter dust cakes is evaluated and discussed. Furthermore video observations of the pulse cleaning event and investigations on the particle aggregation immediately following the cleaning event are analyzed and suggestions towards an improved efficiency of the pulse cleaning are made. For the filtration process itself the permeability of dust cakes is of paramount importance. For the range of porosities above 75% most approaches to calculate the permeability on the basis of porosity and dust properties render poor agreement with experimental data. An extension to the Free-Surface-Model of Happel is proposed that shows a strongly improved accuracy in the predicted permeability when compared to the original model or the Carman-Kozeny correlation.
- OSTI ID:
- 245014
- Report Number(s):
- CONF-950522--; ISBN 0-7918-1305-3
- Country of Publication:
- United States
- Language:
- English
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