Automated fine-particle analysis using scanning electron microscopy

Abstract

Owing to analytical advances, submicron particles as small as 0.1 μm can be characterized for chemical composition, size, and shape using scanning electron microscopy (SEM). Once these characteristics are determined, the individual particles can be grouped into categories that provide size, shape, and chemical/mineral distributions of the fine particle fraction.An important application of submicron particle analysis is in solving ash-related problems in coal combustion and gasification systems. The Energy & Environmental Research Center (EERC) at the University of North Dakota is involved in an international consortium formed by the Electric Power Research Institute (EPRI), with U.S. Department of Energy Morgantown Energy Technology Center support, to study ash-related problems associated with the cleaning of hot gases in advanced energy systems. Before the gases are sent through a gas turbine to produce electricity, the particulates are removed with ceramic filters. Filters designed to trap the ash have a tendency to become plugged with ash, eventually causing operational problems. The focus of the project is to characterize the ashes from several filter systems to determine the mechanisms by which difficult-to-clean ash is formed and how it blinds hot-gas filters.