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Advances in hot gas filtration technique

: Westerheide, R.; Adler, J.


Heinrich, J.G. ; Deutsche Keramische Gesellschaft e.V. -DKG-:
Ceramic Materials and Components for Engines : 7. International Symposium "Ceramic Materials and Components for Engines" - applications in energy, transportation and environment systems
Weinheim: Wiley-VCH, 2001
ISBN: 3-527-30416-9
International Symposium on Ceramic Materials and Components for Engines <7, 2000, Goslar>
Fraunhofer IWM ()

The efficiency of coal fired power plants is mainly a function of the firing process. However the process parameters have to meet the requirements of the raw gas filtration unit, when a gas turbine is used in combined cycle plants. Combined cycle plants are offering an increase of efficiency of about 4% by using new technologies compared to conventional plants. These technologies requiring at least higher operating temperatures. Therefore new materials for higher filtration temperatures in both oxidizing and reducing atmospheres are necessary. Further the lifetime of the filter elements regarding the increased temperature and regarding the element design has to be guaranteed up to 16000 h operating time.
Usually the filter elements are hollow candles made of siliceous bonded silicon carbide with an overall length of 1500 mm. However, the binder is often subjected to creep due to the softening of the binder at high temperatures and the candle may be damaged due to vibrations in the filter unit.
The paper gives an overview about the work in developing new ceramic filter materials based an silicon carbide and alumina. The goal of the development was to increase the potential application temperature. lt was found that the application temperature can be increased up to 900 deg C due to an optimization of binder and sintering process. The analysis of stress distribution in the filter element has shown that the material damage can be reduced by slight optimization of the geometry.