Options
2002
Conference Paper
Titel
Evaluation of mechanical properties and structural changes of ceramic filter materials for hot gas cleaning under simulated process conditions
Abstract
In the combined cycle technology for advanced coal fired power plants at high temperatures up to 950 °C the removal of particles from the stream to the gas turbine is carried out with ceramic filter elements. These elements consist often of siliceous bonded coarse grained silicon carbide. A stable long term operation of the filter elements leads to the demands on good resistance towards thermal, mechanical and chemical loading. The structure of ceramic filter elements consists usually of a highly porous support which ensures the mechanical strength and a layer which operates as the functional part for the particle removal. Thereby the lifetime of the whole element is mainly determined by the lifetime of the support material and not by the functional layer. The durability of the support is limited in principal by materials degradations leading to a decrease of mechanical properties. The decrease or an immediate fracture of a filter element sometimes could be observed. It is assumed that immediate fracture or a crack growth of existing flaws can be caused by vibrations of the filter system. However, it is not possible to measure the vibrations of the filter elements during operation. To get an idea of the vibration behavior of the ceramic elements finite element analysis for the stress and strain behavior for different frequencies as well as experimental investigations in some model experiments were made.