The report describes a new mathematical model for predicting woven glass filter performance with coal fly ash aerosols from utility boilers. Its data base included: an extensive bench- and pilot-scale laboratory investigation of several dust/fabric combinations; field data from three prior GCA studies involving coal fly ash filtration with glass fabrics; past GCA studies of fabric filter cleaning mechanisms; and a broad based literature survey. Trial applications of the model to field filter systems at Sunbury (PA) and Nucla (CO) indicate excellent agreement between theory and practice for both penetration and resistance. The introduction and experimental confirmation of two basic concepts were instrumental in model design: one relates to the way dust dislodges from a fabric and its subsequent impact upon resistance and penetration in a multichambered system; the other, to the relatively large fly ash fractions that pass with minimal collection through temporarily or permanently unblocked pores or pinholes such that observed particle penetrations are essentially independent of size. Cleaning parameters were quantified, and estimates of specific resistance coefficient, K2, were improved.

Prepared by GCA Corporation, GCA/Technology Division, Bedford, Mass., for Environmental Protection Agency, Office of Research and Development, Industrial Environmental Research Laboratory, Research Triangle Park, under contract no. 68-02-1438, task no. 5, program element no. EHE624. Issued Aug. 1977. Includes bibliographical references.