Size-dependent penetration of trace elements through a utility baghouse

Abstract

Particle size-dependent concentrations of 35 major and minor trace elements were measured at the inlet and outlet of a fabric filter baghouse installed on a western pulverized coal-fired power plant. Size-segregated particulate samples were collected using University of Washington impactors with Kapton collection disks coated with Apiezon-L grease. The impactor samples were analyzed for trace elements using neutron activation analysis. The inlet particle size distribution for most elements was bimodal, with the larger mode having a geometric mean diameter of approximately 4–10 μm and the smaller mode having a geometric mean diameter of 0.08 μm or less. In general, individual trace elements exhibited size distributions similar to total mass. However, several elements, including As, Se, Sb, Hg, Cl, Zn and Ni, showed noticeably ‘flatter’ size distributions with proportionally higher concentrations in submicrometer particles compared to total mass. The elemental penetrations through the baghouse generally agreed well with the mass penetration. An exception is Se, which shows penetration an order of magnitude higher than that of total mass and other elements. Most trace elements were removed by the baghouse with greater than 95 % collection efficiency over the entire particle size range.