Particulate hot gas stream cleanup technical issues: Task 1.0, Assessment of ash characteristics. Quarterly report, October-- December 1994

This is the first in a series of quarterly reports describing the activities performed under Task 1. The analyses of Hot Gas Stream Cleanup (HGCU) ashes and descriptions of filter performance presented in this report were designed to address the problems with filter operation that are apparently linked to the characteristics of the collected ash. This task is designed to generate a data base of the key characteristics of ashes collected from operating advanced particle filters (APF`s) and to relate these ash properties to the operation and performance of these filters and their components. Observations of the filter assembly during site visits to the Tidd Demonstration Plant APF have led to the conclusion that that tenacious ash deposits that form in the APF apparently induce stresses that result in bent and/or broken ceramic candle filter elements. A site visit, was made to the Tidd APF on October 27, 1994 to collect ash samples from various locations in the filter vessel and to document the condition of the APF. A variety of laboratory analyses were performed on ash samples collected during this site visit to assess whether recent attempts to introduce larger particles into the ash deposits by derating the cyclone upstream of the APF have been successful. Some particles larger than 45 Jim were identified in various ash samples from the APF, but they account for less than 5 % of the mass of the ash. Although Scanning Electron Microscope EDX spectra and elemental maps lack the resolution to identify the bonds between particles in the ash agglomerates found in the APF, an excellent stereographic image of the structure of an ash nodule collected from the APF was generated with the Scanning Electron Microscope. The stereographic image was very enlightening as to the structure of the nodule