The role of the filter cake in hot gas cleaning with ceramic filters

Experiments were carried out in a pilot-scale test rig at temperatures of 6 00-770 degrees C to investigate the potential of filter cakes formed in hot gas filtration to remove sulfur dioxide, nitric oxide, and alkalis. The re sults demonstrate that a filter cake of fly ash particles is capable of con tributing to SO2 capture, particularly with injection of a fresh sorbent. A filter cake of mixed limestone and alumina particles formed at 600 degrees C showed a higher resistance to flow than one formed at 700 degrees C. The efficiency of SO2 removal increased with the temperature over the range in vestigated. Both the cake and filter absorbed alkalis by chemical reaction, showing that the filter cake will help to protect the gas turbine, as well as the filter itself, against alkali attack. NOx emissions mere not affect ed by the presence of the filter in an oxidizing atmosphere, while a consid erable reduction of NO was obtained in the presence of CO.