Size Distributions, Microstructures, and Elemental Compositions of PM_2.5 from Two Coal-Fired Fluidized-Bed Boilers Equipped with Fabric Filters

Abstract

PM 2.5 is one of the main atmospheric pollutants in China, and coal burning is the main emission source of PM 2.5 . At present, PM 2.5 emission characteristics of the coal-fired fluidized-bed boiler are less to date, especially those of the coal-fired bubbling fluidized-bed (BFB) boiler. In this work, number and mass size distributions, microstructures, and elemental compositions of PM 2.5 produced from a coal-fired circulating fluidized-bed (CFB) boiler and a coal-fired BFB boiler before and after the fabric filter (FF) were studied. Number size distributions of PM 2.5 produced from the CFB boiler before and after the FF are both unimodal, but the ones PM 2.5 produced from the BFB boiler before and after the FF are both bimodal. Mass size distributions of PM 2.5 produced from the CFB boiler and the BFB boiler before and after the FF show no peak. Microstructures of PM 2.5 produced from the CFB boiler are almost all irregular in shape, but the ones produced from the BFB boiler are mainly spherical and irregular. The contents of Si and Al in PM 2.5 produced from the two fluidized-bed boilers before and after the FF are higher compared to those of other elements, and the contents of Cr, V, Mn, Ni, and Pb in PM 2.5 produced from the BFB boiler are higher, and gaseous Na, K, S, and Pb in flue gas can condense into PM 2.5 across the FFs.